Yahoo Inc paid its financial advisers millions of dollars last year to defend the Internet company against Microsoft Corp's unsolicited buyout offer, according to a filing.

Goldman Sachs and Lehman Bros, whose investment banking arm is now part of Barclays Capital Plc, were Yahoo's main financial advisers.

In the U.S. Securities and Exchange Commission filing, Yahoo also said five separate stockholder lawsuits were filed against the company last year relating to the Microsoft proposal.

Microsoft made its $44.6 billion buyout offer for Yahoo public last February and later sweetened it to $47.5 billion before walking away in May.

Yahoo sought an alternative search advertising partnership with archrival Google Inc and also held talks with Time Warner Inc's AOL unit about a potential combination.

Google backed out of the deal later on under regulatory scrutiny, and talks with AOL have not progressed toward a deal after Yahoo co-founder Jerry Yang said he would step down as chief executive.

In January, Yahoo hired Carol Bartz as its new CEO and the company is undergoing a major management reorganization currently.