Global Client top line performance, which grew at 11% on a constant currency basis was once again driven by strong demand for Transformation Services, made up of analytics, digital and consulting.
This quarter, we achieved the milestone of crossing the threshold of $1 billion in quarterly total revenue for the first time.
For the third quarter 2021, we delivered: total revenue of $1.02 billion, up 8% on a constant currency basis; Global Client revenue of $921 million, up 11% on a constant currency basis; adjusted operating income margin of 16.6% compared to 17.1% during the third quarter of 2020; and adjusted diluted earnings per share of $0.66 per share, up 18% year-over-year.
As we deepen our role as a trusted advisor to our clients, we have seen sole-sourced deals, which was, for many quarters, above 50% of our bookings, now rising above 60%.
Global Client Transformation Services continues to grow at a 30%-plus rate and now accounts for more than 35% of total Global Client revenue, including the contribution from the Enquero acquisition.
Year-to-date, approximately 70% of Global Client bookings include a component of analytics, digital or consulting in them.
Analytics is not only the largest component of Transformation Services, contributing more than half of its revenue over the last several quarters, but is also its fastest-growing component, consistently growing well above 30%.
Our intelligence platform, Genpact enterprise 360 enables clients to do just that.
Genpact enterprise 360 harnesses the power of data and insights from our operations built on proprietary metrics and benchmarks we have deployed and developed over the past 20 years in our digital Smart Enterprise frameworks.
As the world continues to adapt to the changes that I've seen over the last 18 months, companies across every industry are intensely competing for talent across the globe.
To date, Almost 70% of our employees are enrolled with more than 43,000 fully trained and tested.
We are delighted to have had a state of recent recognitions for being a great destination for talent in the market, such as: Forbes 2021 World's Best Employers List; the Refinitiv's 2021 diversity and inclusion top 100; a total of 28 excellent awards from Brandon Hall Human Capital Management; International SOS' Duty of Care award for diversity and inclusion; Aptar's top 10 best companies for women in India.
For example, being named to Fortune's Change the World List as one of 100 companies celebrated for having a positive societal impact.
We also recently concluded our annual green-a-thon event with more than 25,000 participants to sponsor the planting of more than 14,500 tree saplings, underscoring our commitment to environmental sustainability.
For example, in our largest delivery ecosystem, India, approximately 80% of our workforce has received at least one dose of a COVID vaccine, and we continue to encourage participation for the rest of our population.
Total revenue was $1.02 billion, up 9% year-over-year or 8% on a constant currency basis.
Global Client revenue that expanded to 91% of total revenue increased 12% year-over-year or 11% on a constant currency basis primarily driven by ongoing movement in Transformation Services led by analytics that grew more than 30% in the quarter as we continued underlying strength in our Intelligent Operations business.
For example, during the 12-month period ended September 30, we grew the number of Global Client relationships with annual revenue over $5 million from 129 to 142 or a 10% year-over-year increase.
This included clients with more than $25 million in annual revenue, increasing from 23 to 26 or 13% year-over-year.
GE revenue declined 15% year-over-year driven by our delivery of committed productivity and the overall macroeconomic impact on GE.
Excluding the effect of revenue related to divested GE businesses I mentioned earlier, GE revenue would have declined 6% during the quarter, which is in line with our expectations.
Adjusted operating income margin at 16.6% declined from the first half of the year largely due to the increase in investment activity that we discussed with you last quarter as well as higher travel expenses.
Gross margin in the quarter was 35.6% compared to 35.2% during the same period last year largely due to increased productivity from higher revenue and a more favorable mix.
We continue to expect our full year gross margin to expand 70 to 75 basis points year-over-year.
SG&A as a percentage of revenue was 21.3%, up 10% year-over-year and 60 basis points sequentially as we dialed up investment activity to be able to take advantage of long-term growth opportunities.
Adjusted earnings per share was $0.66, up 18% year-over-year compared to $0.56 in 2020.
This 10% -- $0.10 increase was primarily driven by higher adjusted operating income of $0.04, lower taxes of $0.03, a $0.02 impact related to FX remeasurement and a $0.01 impact related to lower year-over-year share count.
Our effective tax rate was 17.3% compared to 22.6% last year largely due to discrete benefits in the quarter as well as a nonrecurring prior period tax refund-related items.
Excluding this onetime tax benefit that equates to $0.03 per share, our effective tax rate for the quarter would have been 21.4%.
During the third quarter, we generated $210 million of cash from operation that corresponds to free cash flow being almost two times higher than net income.
This helped drive cash flow from operations of $252 million during the third quarter last year.
Our days outstanding have remained in a consistent range with third quarter 2021 at 84 days.
Cash and cash equivalents totaled $922 million compared to $753 million at the end of the second quarter of 2021, and includes $350 million related to the 1.75% bond that we issued in the first quarter.
We continue to closely monitor market conditions for the optimum timing of the pay down of our 3.7% bond that is scheduled to mature in April 2022.
Our net debt-to-EBITDA ratio for the last four rolling quarters was 1.1 times.
With undrawn debt capacity of approximately $500 million and existing cash balances, we continue to have ample liquidity to pursue growth opportunities and execute on our capital allocation strategy.
Given our year-to-date spending, we now anticipate capital expenditures as a percentage of total revenue for the full year to be in the range of 1.5% to 2%.
We continue to expect total revenue between $3.96 billion and $4 billion, representing year-over-year constant currency growth of 5.5% to 6.5%.
For Global Clients, the expected growth remains in the range of 10.5% to 11.5% or 9% to 10% on a constant currency basis.
There is also no change to our full year GE outlook of approximately 20% year-over-year decline.
Excluding the effect of approximately $40 million in revenue related to the GE divested businesses, we continue to expect GE full year revenue to decline 10% to 12%.
We continue to expect our adjusted operating income margin to expand to 16.5% for the full year.
To be clear, our approximate 16.5% adjusted operating income full year margin remains the baseline for which we think about our trajectory for 2022.
As a result of the nonrecurring tax benefit in the third quarter I referred to earlier, we now expect our full year 2021 effective tax to be approximately 22.5% to 23.5%, which compares to the prior year range of 23.5% to 24.5%.
Given the outlook I just provided, we now expect full year adjusted earnings per share to be in the range of $2.40 to $2.43, up from the prior $2.36 to $2.39 range due to the favorable impact of the nonrecurring tax benefit as well as the balance sheet remeasurement gains during the quarter.
Additionally, given our year-to-date performance, we can now expect our full year operating cash flow to be at least $550 million, up from our earlier outlook of $500 million, and we continue to anticipate free cash flow from operations of approximately 1.2 times to 1.3 times net income, above our historical 1:1 ratio.
This secular trend plays to our strengths in Transformation Services that continues to power our revenue growth led by its largest segment analytics that have been consistently growing more than 30%.

Summary:
For the third quarter 2021, we delivered: total revenue of $1.02 billion, up 8% on a constant currency basis; Global Client revenue of $921 million, up 11% on a constant currency basis; adjusted operating income margin of 16.6% compared to 17.1% during the third quarter of 2020; and adjusted diluted earnings per share of $0.66 per share, up 18% year-over-year.
Total revenue was $1.02 billion, up 9% year-over-year or 8% on a constant currency basis.
Adjusted earnings per share was $0.66, up 18% year-over-year compared to $0.56 in 2020.
We continue to expect total revenue between $3.96 billion and $4 billion, representing year-over-year constant currency growth of 5.5% to 6.5%.
Given the outlook I just provided, we now expect full year adjusted earnings per share to be in the range of $2.40 to $2.43, up from the prior $2.36 to $2.39 range due to the favorable impact of the nonrecurring tax benefit as well as the balance sheet remeasurement gains during the quarter.