The stake was bought from BSE Ltd, country's second largest stock exchange.
"Yes Bank has acquired 500,750 equity shares of liAS from BSE which is equivalent to 5.006% of the paid-up capital of IiAS," said Yes Bank in a notice to stock exchanges. "IiAS is a proxy advisory firm, dedicated to providing participants in the Indian market with independent opinion, research and data on corporate governance issues as well as voting recommendations on shareholder resolutions," it added.
The value of the transaction wasn't disclosed.
Axis Bank, Fitch Group, HDFC, ICICI Prudential Life Insurance, Kotak Mahindra Bank, Tata Investment Corporation and UTI Asset Management Company are some other shareholders in IiAS, as per its website.
The biggest shareholder is the Fitch Group with about 20% stake.