U.S. market index compiler MSCI Inc (MSCI.N) said it was not in talks for a possible takeover.
"We have not received any offer or indication of interest," the company said on Wednesday.
The company's response came after a media report that financial data provider S&P Global Inc (SPGI.N) was seeking to buy MSCI for $11 billion.
MSCI's shares trimmed most of their gains and were up 1 percent. They had risen as much as 13.5 percent to a record high $109.29 in early trading.
Shares of S&P Global were down 1.3 percent at $130.50.
(Reporting by Diptendu Lahiri in Bengaluru; Editing by Sai Sachin Ravikumar)