ISS, a US proxy voting advisory group, may be sold for between $400m (€312m) and $500m, according to an analyst specialising in international corporate governance.

Stephen Davis of Davis Global Advisors said Credit Suisse had been appointed to handle the sale and is distributing offer books to at least five potential bidders, including private equity suitors. The proxy company's main owners are private equity group Warburg Pincus and Hermes Investment Management, the fund manager owned by the pension scheme of UK telecoms group BT. Hermes and Warburg Pincus declined to comment. ISS and Credit Suisse could not be reached for comment. Davis said: "The news will draw immediate attention. ISS is the most powerful vote adviser in North America and Europe." ISS has nearly 1,700 institutional clients and about $25 trillion in assets under advice. Bidders have until next week to submit expressions of interest.