Good day and welcome to the MSCI first quarter 2026 earnings conference call. This press release, along with an earnings presentation, are available on our website, msci.com, under the Investor Relations tab. You'll find a reconciliation of our non-GAAP measures to the equivalent GAAP measures in the appendix of the earnings presentation. Important information regarding our use of operating metrics such as run rate and retention rate are available in the earnings presentation.
Our key financial metrics included organic revenue growth of over 13%, adjusted EPS growth of nearly 14%, adjusted EBITDA growth of almost 19%. We remain long-term believers in the MSCI franchise, and we are committed to maximizing value creation through the disciplined deployment of our excess capital. In addition, we recently completed three very exciting and highly strategic small bolt-on acquisitions in key growth areas. Our Q1 operating metrics included total run rate growth of nearly 13%, fueled by a record asset-based fee run rate of $872 million, growing 25%.
Recurring subscription run rate growth of 9%, fueled by net new recurring subscription sales of $39.6 million, growing 52%. It was our best first quarter for net new recurring subscription sales since 2022. In fact, we posted our strongest ever Q1 on record for recurring sales in APAC at $15 million, up 46% from a year earlier. In index, for example, subscription run rate growth returned to double digits in Q1 at 10.7%.