We ended the year with record organic ASV plus professional services growth of $68 million for the quarter, crossing the $100 million annual ASV threshold for the first time and soundly beating the top end of our guidance.
Our year-on-year organic ASV growth rate accelerated 200 basis points to over 7% and we delivered annual revenue of $1.6 billion and adjusted earnings per share of $11.20.
We accelerated our organic ASV plus professional services growth to 7.2%.
Our buy side and sell side growth rates increased 100 basis points and 400 basis points respectively since the third quarter, reflecting higher sales across our key clients.
ASV growth in the Americas rose to 7% in the fourth quarter, driven primarily by increased sales to our banking, corporate and wealth clients.
Asia-Pac had a record ASV quarter and delivered a growth rate of 12%.
EMEA accelerated to a 6% growth rate, driven by strong performance with data providers, asset managers and banking clients and CTS had the highest contribution to this region, followed by Research.
Research was the largest contributor to our ASV growth this year with a growth rate of 6% driven by very strong growth on the sell side at 12%.
We increased Research workstation users by 86% this quarter versus a year ago with growth across both sell-side and buy-side clients.
Analytics and trading accelerated in the second half in fiscal 2021 versus the first half, ending the year at a 6% growth rate.
CTS grew 16% driven by core company data and data management solutions sold through an increasing number of channels.
Wealth ended the year with a 6% growth rate.
Wealth workstations grew 24% year-over-year and they alongside FactSet's Advisor Dashboard have been the biggest contributors to winning new clients.
Our 7% top line growth this year is a testament to the hard work of our teams and validates our strategy to invest in content and technology, capitalize on market trends and address client needs.
Throughout this fiscal year, we accelerated our growth rate in ASV plus professional services through consistent conversion of our pipeline, delivering over $100 million in ASV growth and surpassing our most recent guidance for the year.
Before I explain the quarterly results, I want to remind everyone that our prior year fourth quarter GAAP results were impacted by one-time non-cash charge of approximately $17 million, related to an impairment of an investment in a third-party.
As you saw on the previous slide, our organic ASV plus professional services growth rate was 7.2%.
For the quarter, GAAP revenue increased by 7% to $412 million.
Organic revenue, which excludes any impact from foreign exchange, acquisitions and deferred revenue amortization also increased 7% to $410 million.
For our geographic segments, organic revenue for the Americas grew to 6%, EMEA grew to 7%, and Asia-Pacific to 12%.
GAAP operating expenses grew 3% in the fourth quarter to $293 million, impacted by a higher cost of services.
Compared to the previous year, our GAAP operating margin increased by 320 basis points to 28.9% and our adjusted operating margin decreased by 150 basis points to 31.6%.
As a percentage of revenue, our cost of services was 10 basis points higher than last year on a GAAP basis and flat to last year on an adjusted basis.
SG&A expenses when expressed as a percentage of revenue improved year-over-year by 330 basis points on a GAAP basis, but increased 170 basis points on an adjusted basis.
Moving on, our tax rate for the quarter was 15% higher than the prior year's tax rate of 7% primarily due to lower tax benefits associated with stock-based compensation in the current quarter as well as a tax benefit related to finalizing the prior year's tax returns.
GAAP earnings per share increased 15% to $2.63 this quarter versus $2.29 in the prior year.
Adjusted diluted earnings per share remained flat year-over-year at $2.88.
Free cash flow which we define as cash generated from operations less capital spending was $171 million for the quarter, an increase of 18% over the same period last year.
For the fourth quarter, our ASV retention remained above 95% and our client retention improved to 91%, which again speaks to the demand for our solutions and excellent execution by our sales team.
Compared to the prior year, we grew our total number of clients by 10% over 6,400, largely due to the addition of more wealth and corporate clients.
And our user count grew 14% year-over-year and crossed the total of 160,000, primarily driven by sales in our wealth and research solutions and in particular in the number of banking users.
For the quarter, we repurchased over 265,000 shares of our common stock at a total cost of $93 million, with a average share price of $348.
For the year, we repurchased $265 million of our shares and increased our dividend for the 22nd consecutive year.
With share repurchases and dividends on an annual basis, we have returned to shareholders almost 70% as a percentage of free cash flow and proceeds from employee stock option.
For organic ASV plus professional services, we are guiding to an incremental $105 million to $135 million.
The midpoint of this range represents a 7% increase, which is equal to this year's organic growth rate, reflecting continued momentum in our business.

Summary:
GAAP earnings per share increased 15% to $2.63 this quarter versus $2.29 in the prior year.
Adjusted diluted earnings per share remained flat year-over-year at $2.88.