Total company revenues were up 16% with strength in all three business segments and research exceeding our expectations.
Total contract value growth increased to 11% with both GTS and GBS accelerating in the quarter.
For Q2, GTS contract value growth accelerated to 9% and we have CD growth in all of our top 10 countries.
GBS again accelerated, delivering outstanding contract value growth of 18%.
And our HR, finance, sales and supply chain practices each exceeded 20% contract value growth.
Turning to conferences; for the second quarter of 2021, conferences revenues were $58 million, again exceeding our expectations.
Consulting revenues were up 4% in Q2.
With labor-based revenue up 20% over this time last year.
Second quarter revenue was $1.2 billion, up 20% year-over-year as reported and 16% FX neutral.
In addition, total contribution margin was 70%, up more than 300 basis points versus the prior year.
EBITDA was $355 million, up 85% year-over-year and up 75% FX neutral.
Adjusted earnings per share was $2.24.
Free cash flow on the quarter was $563 million.
Free cash flow includes $150 million from insurance proceeds related to cancelled 2020 conferences.
Research revenue in the second quarter grew 15% year-over-year as reported and 11% on an FX neutral basis.
Second quarter research contribution margin was 74%, up about 170 basis points versus 2020.
Total contract value grew 11% FX neutral year-over-year to $3.8 billion at June 30.
Quarterly net contract value increased or NCVI was $114 million, significantly better than the pandemic lows in the second quarter of last year and a new record high for second quarter NCVI.
Global technology sales contract value at the end of the second quarter was $3 billion, up 9% versus the prior year.
GTS CV increased $75 million from the first quarter.
While retention for GTS was 101% for the quarter, up about 110 basis points year-over-year.
GTS new business was up 38% versus last year with strength in new logos and continued improvement in upsell with existing clients.
Global Business Sales Contract Value was $770 million at the end of the second quarter, up 18% year-over-year, which is above the high-end of our medium term outlook of 12% to 16%.
GBS CV increased $39 million from the first quarter.
HR, finance, sales and supply chain each grew 20% or more year-over-year.
While retention for GBS was 110% for the quarter, up more than 950 basis points year-over-year.
GBS new business was up 76% over last year, led by very strong growth across the full portfolio.
Conferences revenue for the second quarter was $58 million compared to no revenue in the year-ago quarter.
Contribution margin in the quarter was 73% driven by strong top line performance.
We held 13 virtual conferences in the quarter.
Second quarter consulting revenues increased by 9% year-over-year to $106 million.
On an FX neutral basis, revenues were up 4%.
Consulting contribution margin was 40% in the second quarter, up almost 600 basis points versus the prior year quarter.
Labor-based revenues were $86 million, up 25% versus Q2 of last year and up 20% on an FX neutral basis.
Labor-based billable headcount of 740 was down 7%.
Utilization was 70%, up more than 1,100 basis points year-over-year.
Backlog at June 30 was $108 million, up 7% year-over-year on an FX neutral basis after another strong bookings quarter.
Our Contract Optimization business was down 31% on a reported basis versus the prior year quarter and down 33% FX neutral.
Consolidated cost of service has increased 9% year-over-year and 6% FX neutral in the second quarter.
SG&A decreased 1% year-over-year and 4% FX neutral in the second quarter.
EBITDA for the second quarter was $355 million, up 85% year-over-year on a reported basis and up 75% FX neutral.
Depreciation in the quarter was up about $3 million versus 2020, reflecting real estate and software which went into service since the second quarter of last year.
Net interest expense excluding deferred financing costs in the quarter was $26 million, roughly flat versus the second quarter of 2020.
The Q2 adjusted tax rate which we use for the calculation of adjusted net income was 29.9% for the quarter.
The tax rate for the items used to adjust net income was 24.6% in the quarter.
Adjusted earnings per share in Q2 was $2.24.
The weighted average fully diluted share count for the second quarter was 86.6 million shares.
We exited the second quarter with 85.1 million fully diluted shares.
Operating cash flow for the quarter was $575 million, up 68% compared to last year.
Q2 operating cash flow includes $150 million of proceeds from insurance related to 2020 conference cancellations.
Excluding the insurance proceeds, operating cash flow improved by 24% versus the prior year quarter.
Capex for the quarter was $12 million, down 44% year-over-year.
Free cash flow for the quarter was $563 million, which was up about 75% versus the prior year.
Excluding the insurance proceeds, free cash flow improved by 28% versus the prior year quarter.
Free cash flow as a percent of revenue or free cash flow margin was 27% on a rolling four quarter basis.
Excluding the insurance proceeds, free cash flow was 23% of revenue, continuing the improvement we've been making over the past few years.
At the end of the second quarter, we had $796 million of cash.
During the quarter, we issued $600 million of new 8-year senior unsecured notes with a 3.625% coupon.
We used the proceeds from this new issuance to repay $100 million of the existing term loan A. The balance is available for general corporate purposes including share repurchases.
Our June 30 debt balance was $2.5 billion.
At the end of the second quarter, we had about $1 billion of revolver capacity.
Our reported gross debt to trailing 12-month EBITDA was about 2.3x.
During the quarter, we made a small acquisition with net cash paid at closing of $23 million.
Year-to-date, we've repurchased more than $1 billion in stock, including $685 million during the second quarter.
In July, the Board increased our share repurchase authorization for the third time this year, adding another $800 million.
As of August 1, we have more than $1 billion available for share repurchases.
For our revenue guidance, we now expect research revenue of at least $4 billion, which is growth of 11%.
We still expect Conferences revenue of at least $170 million, which is growth of 41%.
We still expect Consulting revenue of at least $400 million, which is growth of 6%.
The result is an outlook for consolidated revenue of at least $4.57 billion, which is growth of 11%.
Based on current foreign exchange rates and business mix, the consolidated growth includes an FX benefit of about 200 basis points.
We now expect full year adjusted EBITDA of at least $1.16 billion, which is an increase of about 42% versus 2020 and reflects reported margins of 25.4%.
We expect a reasonable baseline for thinking about the margins going forward is around 18% to 19% consistent with our comments last quarter.
We expect our full year 2021 adjusted net interest expense to be $113 million.
Looking out to 2022, as the balance sheet stands today, we expect interest expense to be around $115 million.
We expect an adjusted tax rate of around 22% for 2021.
We now expect 2021 adjusted earnings per share of at least $7.60.
For 2021, we now expect free cash flow of at least $1.13 billion.
This includes the $150 million of insurance proceeds received in the second quarter this year.
For Q3, we expect to deliver at least $250 million of EBITDA.
With 12% to 16% Research CV growth, we will deliver double-digit revenue growth.
With gross margin expansion, sales cost growing in line with CV growth over time, and G&A leverage, we can modestly expand margins from a normalized 2021 level of around 18% to 19%.
We repurchased more than $1 billion worth of stock this year, and remain committed to returning excess capital to our shareholders.

Summary:
Second quarter revenue was $1.2 billion, up 20% year-over-year as reported and 16% FX neutral.
Adjusted earnings per share was $2.24.
Adjusted earnings per share in Q2 was $2.24.