Good day, and thank you for standing by. Welcome to Certara fourth quarter 2021 earnings conference call. At this time, all participants are on a listen-only mode. After the speaker presentation, there will be a question-and-answer session. To ask a question during the session, you will need to press star one on your telephone. Please be advised that today's conference is being recorded. If you require any further assistance, please press star zero. I would now like to hand the conference over to your first speaker today, to Mr. David Deuchler, Investor Relations. You may begin.
Good afternoon, everyone. Thank you all for participating in today's conference call. On the call from Certara, we have William Feehery, Chief Executive Officer, and Andrew Schemick, Chief Financial Officer. Earlier today, Certara released financial results for the quarter ended December 31, 2021. A copy of the press release is available on the company's website.
Before we begin, I'd like to remind you that management will make statements during this call that include forward-looking statements within the meaning of federal securities laws, which are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Any statements contained in this call that relate to expectations or predictions of future events, results, or performance are forward-looking statements. Actual results may differ materially from those expressed or implied in the forward-looking statements due to a variety of factors.
For a list and description of the risks and uncertainties associated with Certara's business, please refer to the Risk Factors section of our Form 10-K filed with the Securities and Exchange Commission on March 1st, 2022, which will be filed shortly after this call. We urge you to consider these factors, and you should be aware that these statements should be considered estimates only and are not a guarantee of future performance.
Also, in their remarks or responses to questions, management may mention some Non-GAAP financial measures. Reconciliations of adjusted EBITDA, adjusted net income, adjusted EPS, and certain other Non-GAAP financial measures to the most directly comparable GAAP measures are available in the recent earnings release, which is available on the company's website. The conference call contains time-sensitive information and is accurate only as of the live broadcast today, March 1st, 2022.
Certara disclaims any intention or obligation, except as required by law, to update or revise any financial projections or forward-looking statements, whether because of new information, future events, or otherwise. With that, I will turn the call over to William.
Thank you, David. Good afternoon, everyone. Thank you for joining Certara's fourth quarter and full year earnings call. Andrew and I will start with prepared remarks, and then we will take questions. 2021 was a milestone year for Certara. It was our first full year as a public company, and we made progress on a number of key priorities and initiatives.
We are very excited about the opportunities ahead, and as we continue delivering on our mission to accelerate the drug development process with our proprietary biosimulation software, technologies, and services. At Certara, our strategy is to transform the drug R&D process with our end-to-end platform, powered by innovative technology and our global team of leading experts. We not only speed up the process, but also help to advance safety and efficacy of drugs for millions of patients worldwide.
For the full year, we reported total revenue of $286 million, growing 17% year-over-year, including Pinnacle 21, and 15% excluding Pinnacle 21's contribution in the fourth quarter. 2021 revenue growth was in the double digits in every region of the world. Fourth quarter total company revenue was $75.3 million, growing 17% versus the same period a year ago. Pinnacle 21 contributed $6.1 million in the quarter.
Excluding Pinnacle 21, revenue was $69.2 million, growing 7% compared with the same period a year ago. Excluding Pinnacle 21, fourth quarter software revenue was in line with expectations, growing 13% compared with the fourth quarter of 2020. Technology-driven services came in below our expectations, growing 6% compared with the fourth quarter of 2020.
Our technology-driven services performance in the fourth quarter was driven by two issues, both of which impacted the timing of work being executed. First, as we commented in our third quarter earnings call in November, we have been experiencing variability in the timing of our regulatory services projects due to COVID-19-related delays.
We did not have cancellations, and our bookings and regulatory services projects continued to be strong. As you recall, in Q3 2021, we experienced significant growth, 28% year-over-year in technology-driven services due to the recognition of delayed regulatory services projects. In Q4, the COVID-19-related slowdown in closing out clinical trials impacted timing of projects and revenue recognition in regulatory, which resulted in a shortfall in Q4 in services.
In the back half of the year, technology-driven services revenue grew 16% year-over-year, and we expect it to continue growing in the mid-teens in 2022. We expect these delays will moderate in 2022, and we will recapture most of this regulatory services revenue over the course of the year. We continue to work hard to manage consistent conversion of our bookings billings to smooth out our revenue recognition throughout the year.
Second, the surge in COVID-19 cases resulting from the Omicron variant reduced the capacity of our employees and clients in the back half of the fourth quarter. We believe that these are transitory factors that we are well-equipped to manage in 2022.
As we look forward to the coming year, we remain optimistic about activity returning to more normal levels as the year progresses, with conferences coming back and more people back in the office. Turning to software, we were pleased with our performance during the fourth quarter, which grew 46%, including Pinnacle 21, and 13% excluding Pinnacle 21.
The growth was driven by a 96% software renewal rate and strong demand for our proprietary biosimulation software, our Phoenix and Simcyp platforms, and Pinnacle 21 also delivered according to our expectations. As we mentioned at our December Investor Day, we see a number of compelling opportunities ahead for Certara and software, and we've increased our investment to support those R&D activities in 2022.
Specifically, we're focused on expanding the use cases of our Simcyp Simulator, which continues to grow in adoption to reduce or waive drug-drug interaction and bioequivalent studies, as well as support better dosing for special patient populations. Looking to 2022, we expect strong momentum in software to continue, and we believe the transitory headwinds experienced in regulatory services projects during the fourth quarter will subside over the course of the year.
Booking trends in both software and technology-driven services remain strong. Fourth quarter bookings grew 30% year-over-year, and trailing 12-month bookings grew 18% over the prior period, including the contribution from Pinnacle 21. As such, we remain well-positioned to achieve our long-term financial and strategic plans. Moving to performance for the year.
In 2021, we drove strong growth in new customers, and we now serve more than 2,000 customers, including more than 350 additional software end customers who engage with us through our distributors in Asia Pacific. Our land and expand strategy has also delivered solid growth among existing customers.
We ended the year with 299 customers with annual contract value of more than $100,000, representing growth of 15% year-over-year. The integration of Pinnacle 21 into our software group was an important focus in the fourth quarter. We are now beginning to execute on the promise of the compelling opportunities identified when we acquired Pinnacle 21.
In December, we released the latest version of the Pinnacle 21 Enterprise software, which offers immense value to experts in biostatistics and biometrics in ensuring that submissions to regulatory agencies comply with data standards requirements. The feature-rich release proactively supports the new Define-XML 2.1 data standard. This is the first of many growth milestones we expect to emerge from the Pinnacle 21 platform.
Updating Certara software remains a top priority for our team, and we continue to innovate during the fourth quarter with the release of Simcyp Simulator version 21 and D360 Scientific Informatics Software version 21.5. The latest update to the Simcyp Simulator aligns with recent regulatory guidances, and it includes other updates to support customers' development priorities, including additions to the compound library to facilitate drug-drug interaction analysis and updates to our renal and hepatic-impaired population models.
The latest version of D360 software increases efficiency in analyzing and guiding the design of small molecule drugs and biologics. We remain very encouraged by the growing pipeline and opportunity for our software to advance discovery research. During the quarter, we announced that the FDA has renewed and expanded licenses of Certara's biosimulation software with more than 400 user licenses of Simcyp and Phoenix platforms across 12 divisions and offices.
The FDA also recently licensed our immunogenicity simulator for the first time to research and evaluate immunogenicity and regulatory submissions for biologics. Immunogenicity, or the tendency of protein-based therapeutics to trigger an immune response, is a major problem in drug development. Our immunogenicity simulator predicts the immunogenicity incidence of therapeutics to guide dosing and study design for better clinical outcomes for patients.
It continues to be a privilege for us to provide software that global regulatory agencies can rely on to inform their reviews of regulatory submissions. 2021 was also the eighth consecutive year that Certara's customers received 90% of the novel drug approvals by the FDA, excluding diagnostic products. The Simcyp Simulator was used in 13 of these approvals to inform the drug label. We are excited by the recent launch of the FDA's Project Optimus initiative, which aims to reform the dose optimization and dose selection paradigm in oncology drug development.
This is important for drug developers and patients because the current approach of maximum tolerated dose may lead to selection of a dose that provides more toxicity without additional efficacy. Certara is well positioned to address these upcoming changes in dose finding and the evolving regulatory landscape with our extensive experience in oncology as well as dose optimization, trial design, regulatory strategy and submissions.
As outlined in our strategy, we continue to invest in the business and add to our expert team worldwide. Toward the end of the year, we experienced an increase in attrition due to a variety of factors. Our attrition was fairly low in 2020, so now we're getting back to more normal levels of attrition that we had experienced pre-COVID. We continue to prioritize adding top talent, and in 2021, we hired leading scientists and subject matter experts to support our ongoing growth.
We ended the year with approximately 1,100 employees, including more than 350 employees with doctorate degrees. Certara's culture and commitment to innovation and customer partnerships continue to attract top talent in a competitive hiring environment. We remain focused on making Certara the employer of choice in the industry. In summary, I'm pleased with the performance of the company in 2021, delivering double-digit growth in software and services, advancing the adoption of biosimulation and acquiring and integrating Pinnacle 21.
While revenue from our regulatory services business in the fourth quarter did not meet our expectations, our bookings growth and our momentum remained strong. I am confident in our Certara team to execute our plan. I will now turn this over to our CFO, Andrew Schemick, to discuss the fourth quarter and full-year financial results in more detail.
Thank you, William. Hello, everyone. Total revenue for the three months ended December 31, 2021 was $75.3 million, representing year-over-year growth of 17%. Excluding Pinnacle 21, fourth quarter revenue growth was 7%. Full year 2021 reported revenue was $286.1 million, which represents 17% year-over-year growth. Excluding Pinnacle 21, full-year revenue grew 15% in line with our long term plan despite the unexpected performance of our technology-driven services business in the fourth quarter.
We are very well positioned for 2022, with trailing twelve months bookings coming in at $341.7 million, up approximately 19% year-over-year on a reported basis, and up approximately 16% excluding Pinnacle 21. I continue to look at trailing twelve months bookings as a predictor of forward twelve months revenues.
Book-to-bill has been stable, ending the year at 1.19 times, and the annual bookings in 2021 as a percentage of forward revenue supports the visibility into our guidance for the year. Software revenue was $25.5 million in the fourth quarter, which increased 46% over the prior year period. Excluding $5.7 million in Pinnacle 21 software revenue contribution, year-over-year growth was 13%. The growth in the quarter, excluding Pinnacle 21, was driven by our biosimulation software, Simcyp and Phoenix.
For the full year, software revenue was $86.8 million, representing 18% growth as compared to 2020. Excluding Pinnacle 21, year-over-year growth for the full year software revenue was 10%, driven by Simcyp, Phoenix and Integral. Software bookings were $32.3 million in the fourth quarter, which increased 54% from the prior year period.
Pinnacle 21 contributed $8.2 million to software bookings in the fourth quarter. Q4 year-over-year software bookings growth excluding Pinnacle 21 was 15%. Trailing twelve-month software bookings were $94.5 million, up 29% over the 2020 software bookings. Software aggregate renewal rate was 96% in the fourth quarter and 92% for the full year in 2021. Services revenue was $49.8 million in the fourth quarter, which increased 6% over the prior year period.
As William mentioned, relative weakness in technology-driven services was due to the delays in closing clinical trials impacting regulatory services projects and lower employee utilization rates in technology-driven services towards the end of the quarter. For the full year, services revenue was $199.3 million, representing growth of 17% year-over-year.
Looking at the second half of the year, services revenue was $104.4 million, up 16% over the same period last year. Technology-driven services bookings in the fourth quarter were $80.2 million, which increased 27% from the prior year period. Services bookings for the full year were $247.2 million, which increased 15% as compared to 2020. Moving further down the P&L for fourth quarter results. Total cost of revenue for the fourth quarter of 2021 was $29.3 million, a decrease from $34.9 million in the fourth quarter of 2020, primarily due to a $7.2 million decrease in stock-based compensation expense.
Total operating expenses for the fourth quarter of 2021 were $42.6 million, a decrease from $83.3 million in the fourth quarter of 2020. The components of operating expenses are as follows. Sales and marketing expenses were $6.7 million compared to $10.4 million for the fourth quarter of 2020, lower due to a $6.7 million decrease in stock-based compensation, partially offset by employee-related costs resulting from increased investments in the commercial operations and sales force expansion. R&D expenses were $6.5 million compared to $10.5 million for the fourth quarter of 2020.
The decrease in R&D expenses was primarily due to a $5.7 million decrease in stock-based compensation, partially offset by increases in employee-related costs resulting from headcount growth. SG&A expenses were $18.7 million compared to $52.4 million for the fourth quarter of 2020. The decrease was primarily due to a $34 million decrease in stock-based compensation expense.
Intangible asset amortization was $10.2 million compared to $9.4 million in the fourth quarter of 2020, higher due to acquired intangible assets. Depreciation expense was $0.5 million, down slightly compared to last year. Continuing down the P&L, interest expense during the fourth quarter was $3.3 million compared to $5.5 million for the fourth quarter of 2021, a decrease due primarily to lower average outstanding principal balance on our credit facilities.
Income tax expense was $9.5 million as compared to an income tax benefit of $5.5 million in the prior year, due primarily to the relative mix of domestic and international earnings, as well as the impact of rate changes in foreign jurisdictions and the impact of nondeductible items. Net loss for the fourth quarter of 2021 was $9.7 million compared to a net loss of $54.4 million in the fourth quarter of 2020.
Diluted loss per share for the fourth quarter was $0.06 as compared to $0.40 in the fourth quarter of 2020. Adjusted EBITDA for the fourth quarter of 2021 was $28.2 million compared to $22.2 million for the fourth quarter of 2020, representing 27% growth.
For the full year, adjusted EBITDA was $103.7 million, representing 18% growth over 2020. Adjusted net income for the fourth quarter of 2021 was $1.4 million compared to $10.3 million for the fourth quarter of 2020, a decrease due to the increase in provision for income taxes and acquisition amortization. Adjusted diluted earnings per share for the fourth quarter of 2021 was $0.01 compared to $0.07 for the fourth quarter of 2020. Now moving to the balance sheet. We ended the quarter with $185.8 million of cash and cash equivalents.
As of December 31, 2021, we had $295 million of net outstanding borrowings on our term loan and full availability under our revolving credit facility. We are making an adjustment to our guidance based on what William discussed earlier around transitory COVID-related impacts to our regulatory services business.
We are lowering the top end of the range for revenue from $370 million to $360 million and lowering the top end of the range for EBITDA from $135 million to $131 million. We are maintaining the lower end of the ranges for revenue and EBITDA, reflecting our continued confidence in the strong growth in bookings and our dedication to delivering on our strategic and financial plans.
Revenue in the range of $350 million-$360 million, which represents growth of 22%-26% year-over-year and 15%-18% year-over-year growth, excluding Pinnacle 21. Adjusted EBITDA in the range of $127 million-$131 million. Adjusted EPS in the range of $0.48-$0.53 per share. Fully diluted share in the range of 156 million-159 million. GAAP tax rate in the range of 40%-45% and cash tax rate in the range of 20%-25%. Thank you. Now we will open up the line for questions. Operator, can you open the line?
Thank you, sir. As a reminder, to ask a question, you will need to press star one on your touchtone telephone. To withdraw your question, please press the pound key. Please stand by while we begin our Q&A process. Our first question comes from the line of Luke Sergott from Barclays. Please go ahead.
Hey, guys. Thanks for the questions. I guess given the duration of the business and the visibility you guys have, you had to step down in Q3 in the bookings and then kind of that flowed through into Q4. I'm just wondering, you talked about getting this business back throughout the year. Why wouldn't it come back earlier? Are you still seeing some weakness due to Omicron? I'm just trying to get a better understanding of the dynamics.
Yeah, Luke, thanks for the question. We saw weakness pop up quite suddenly at the end of the fourth quarter. It continued into January, although it seems like we are through that now. You know, our view is that, you know, two things happened to us in the fourth quarter. One was due to Omicron, our own internal capacity, and then the other one is this, you know, we saw some lengthening of time between when particularly regulatory customers have booked our
Have done bookings with us and actually have gotten the data ready for us to do work. You know, all things considered, as we look forward to the year based on what we know for the first, you know, two months now, we think, you know, our guidance of $350-$360 makes the most sense.
Yeah. Just to follow up on that, I mean, it's because it's really early in the year, and it's just to not think that you're gonna get it back. What gives you the, like, what's the. Is it getting pushed out to 2023 now due to the regulatory stuff, or is this business that was lost?
No, we didn't lose any bookings, but we have seen this lengthening of time from, particularly from a number of customers from their database lock, which is really what kind of kicks off this type of work for us. It's possible this will reverse during the year, but we're, you know, we kinda have to call it the way we see it with the two months of data that we've got so far. I don't know, Andy, if you wanna comment on any of this.
No, that's consistent with my view.
Okay, thanks. I'll jump back in the queue.
All right. Thanks, Luke.
Yep.
Thank you. Our next question comes from the line of John Kreger from William Blair. Please go ahead.
Hey. Thanks very much. Just following up on that, Andy, can you remind us what's the % of your revenue that is regulatory services related as opposed to the other buckets? Maybe now that you've got another full year, if you could just sort of give us some of those main categories as you have in the past, that'd be helpful.
Sure. Thank you for the question. The mix this year in terms of revenues was 30% software, 40% Biosim services, 30% regulatory and access services. It's fairly consistent with last year. Slight mix shift towards Biosim services.
Got it. Thank you. Should we be thinking about the slowing that you had in Q4 as sort of a push into Q1? In other words, would you assume your Q1 might be even a little bit elevated, or should we assume that kind of given that the Omicron surge carried through a chunk of January, Q1 would be sort of slower and then the momentum would build as you move through the year?
In putting together our guidance, we incorporated the second point of view. Given the data that we've seen so far in January and mid-February, we're starting to see some pickup, but certainly not a push into Q1.
Got it. Thanks. One more, Bill, this might be for you. There's been a lot of anxiety about kind of smaller biotech-oriented clients being under pressure and not having the same sort of funding momentum. Can you remind us how big of a chunk of revenues come from biotech, and are you seeing any change in behavior from them today?
Yeah. We've been aware of a lot of comments about that, but we haven't seen it in our business. Our biotech business grew quite nicely through 2021 and even in the fourth quarter in terms of our bookings. I think our view is that you know, there was a couple of quarters of slowdown in biotech funding that came after a couple of years of quite healthy biotech funding.
You know, there's just a lot of well-funded companies out there that are great customers for us. I think there may be some aspect of you know, when funding gets a little bit tighter, then maybe people get even more interested in becoming more efficient by using biosimulation.
Great. Thanks. Can you give us a number about roughly what % of revenue come from small biotechs without sales?
Referred annually?
We don't disclose that number, but it's a small percentage of the overall company revenues. 50% of the revenues come from the top 20. So it's not a major fraction. A healthy biotech that's having some success given the type of work that we do becomes a more significant customer, but early stage is a small fraction.
Okay. Thank you.
Thank you. Our next question comes from the line of Dave Windley from Jefferies. Please go ahead.
Hi. Could you talk about your success? You talked about, Bill, the Enterprise release on Pinnacle 21, and I think part of your strategy was to see what conversion you could encourage from the free accounts, the premium accounts to Enterprise customers. Could you just give us an update on where that stands and what your outlook is for that?
Yeah. Thanks, David. Pinnacle 21 performed in the fourth quarter almost right down the fairway with what we had expected when we did the acquisition. We, you know, obviously spent the quarter, you know, getting to know each other and integrating. As we go forward this year, there's opportunities for you know, cross-selling with each other's customers.
We still have a strong freemium customer base, you know, over particularly as some of the small biotech customers start going, you know, start becoming successful and filing to the FDA. Some of them have converted over. You know, I think, there's a combination of, you know, in terms of strategy there, in terms of what you're talking about is how do we convert some to the freemium.
We have a pipeline of some, you know, some new products that are coming out over the next couple of months. You know, we'll come back and, you know, sort of stay tuned. You know, throughout 2021 we have some new things coming out in Pinnacle 21 as well.
Okay. Thank you for that. A little bit of a corollary, I suppose, or another version of John's question on mix of clients. I think it's logical to us that your biotech clients or your you know, mid to smaller clients lean more towards services. Services are gonna naturally be lower margin than a pure software purchase. But if you look at apples to apples, is a pharma service, a larger client, services client versus a small services client, similar margin? Or would there be differences, apples to apples, on those bases?
Andy, how do we wanna disclose this?
Yeah.
I would say that for a small biotech, it's profitable in terms of the value that we're bringing to the biotech. For a large pharma company we can run the projects more efficiently, so I don't see a mix shift in terms of margins from shifting from what we look at as the top fifty versus or the tier one versus tier two and tier three.
Okay.
So the las question... Sorry, go ahead.
No, go ahead, David. Thank you.
I was just gonna say, related to Project Optimus and maximum tolerated dose, changes in philosophy at the FDA, do you have any thoughts on, I mean, I listened to your webinar the other day, that your colleagues put on. How quickly can this have an impact or an influence over, customers changes in the way that they pursue their early stage, you know, oncology work and dose escalation and, you know, that then result in potentially some bookings for your products in trying to triangulate on those optimal doses?
Yeah. The FDA has already started to encourage this. As you said, we had a quite large webinar talking about it the other day. We have already started projects related to Optimus. I guess the answer is that, you know, the half of, you know, maybe half of drug R&D spending goes into oncology overall. You know, probably a similar fraction of our effort in Certara is associated with that because, you know, we tend to mirror the pharma industry. As those customers are implementing Optimus, that presents a, you know, an increasing opportunity for us, but it starts now.
Okay. Would you view that as new revenue, that's incremental revenue, not, say, cannibalizing something else that you do for those clients?
Yeah, no, we see this as a new revenue opportunity for us. You know, look, a lot of biosimulation focuses on optimizing the dose between safety and efficacy. Oncology customers have been at one end of the spectrum for a long time, right? They, you know, if you're gonna give the maximum tolerable dose, then sort of the dosing calculation is easier. Now it's a little bit more complex. We have a lot of, you know, our services and our software are quite valuable, I think, for this. It should be a good opportunity for the company.
Okay. That's great. I appreciate the perspective. Thank you.
Thank you.
Our next question.
Thank you.
Thank you. Our next question comes from the line of Michael Ryskin from Bank of America. Please go ahead.
Hey, good afternoon. It's Derik De Bruin in for Michael Ryskin. Hey, just a little bit of clarity on how should we think about the step-up in revenues from Q4 Q1, or are you expecting flattish? I mean, historically, I mean, given the two quarters, it seems like a low single digit step-up is what you're seeing. Is that something? Is that similar or are we looking more flattish now Q to Q?
Well, we're looking at, I would say more like low single digit step-up.
Great. Thank you. As we look at OpEx, you talked about, you know, retaining people and doing like that. Is there any incremental headcount spend, OpEx spending, SG&A spend that we need to sort of incorporate relative to what you had said on the analyst day?
We continue to, you know, invest in our commercial organization, our sales and marketing efforts. We also continue to invest in our corporate infrastructure in terms of OpEx. However, you know, no difference from the assumptions that we provided at the investor day.
Got it. Just some other cleanup, interest expense for the year.
Interest expense for 2022?
Yes, sir. Yeah.
$15.3 million.
Great. Thank you. Just, one other one. I mean, just reiterating, no cancellations, it's all push out and you're just being very conservative based upon what you see at this point in the year.
Yeah. We had really no significant cancellations. We had actually quite healthy bookings in Q4. We did see some of the same slowdown that we saw in December, in early January. As we moved into February, that seems like things have picked up, though.
Great.
healthy, and we didn't lose any significant business.
Thanks.
Thank you. As a reminder, to ask a question, you would need to press star one on your telephone. To withdraw your question, please press the pound key. I show our next question comes from the line of Vikram Kesavabhotla from Baird. Please go ahead.
Yeah, thanks for taking the questions. I just wanted to follow up on some of your comments around the workforce. I think you mentioned that there was increased attrition towards the end of the year. Could you just give us some more color on some of the drivers behind that dynamic and what you're seeing so far this year? I guess going forward, I'm wondering if you can just put a finer point on your expectations around headcount growth in fiscal 2022 and maybe what parts of the business or what geographies you're most focused on from a hiring perspective.
Yeah, thanks, Vikram. We saw quite low turnover through in 2020 and through the first half of 2021. Like a lot of companies, we saw some increased turnover in the second half of 2021. If you average it over 2021, though, it was probably at or maybe even lower than our historical average. I think it might have been a, you know, maybe a delayed reaction to people hanging on there in the beginning of the year.
You know, our turnover rate is always something we pay a lot of attention to because, you know, we want Certara to be a place where software developers and drug developers come and, you know, innovate and do some really amazing work. You know, we do pay a lot of attention to this.
We've seen it, you know, we've seen probably improve as we've gone into the first half of this year or the first part of this year rather. For the second part of your question, maybe I'll ask Andrew to comment around the budget for this year. Yeah. We've seen, you know, the delays that we have referenced earlier also had some impact on Q4 bookings. We're seeing healthy bookings going into the year this year. In line with that, we're looking at expanding our billable headcount by around 18% in 2022.
Okay. Great. Thank you. I apologize if I missed this, but could you clarify what the fiscal 2022 revenue guidance assumes for growth rates across biosimulation, market access, and regulatory? I think you gave some color on those different components at the investor day. I just wanna make sure we understand the new range appropriately. Thanks.
Sure. In terms of growth rates, it would be, you know, high teens, mid- to high-teens for the biosimulation and low- to mid-teens for the regulatory. The difference being historically they would grow similar growth rates, but the delays are having the greatest impact on the regulatory side.
Okay. Thank you.
Thank you. I'm showing no further questions in the queue. At this time, I'd like to turn the call back over to Mr. William Feehery, CEO for closing remarks. Please go ahead.
Thanks very much. Thanks everybody for joining tonight. I think that the message I'd like to leave everybody with is, you know, we had some temporary lengthening of some regulatory projects coupled with an unfortunate timing around Omicron. Fundamentally, we believe the company is very healthy.
You know, to support that, I look at the strength of our bookings, which were quite good, both for the full year of 2021 and as we finished the year. We've seen, you know, as I said earlier, we saw a continuation of the Omicron delays in the first part of January, but that seems to have been ameliorated and things have been picking up as we went into February.
Our guidance change is, you know, based on, you know, what we see right now in terms of, you know, we haven't lost any work. You know, some things have stretched out and they've slipped. But fundamentally, we think as we go through 2022, we should see an acceleration. The overall market is healthy, company is healthy, and we feel quite excited about our future. I'll wrap up now and say thank you to everybody for joining us tonight.
Thank you.
Thank you.
This concludes today's conference call. Thank you for participating. You may now disconnect. Good day.