Yahoo! Inc. advisers Allen & Co. and Goldman Sachs Group Inc. are reportedly insisting that potential bidders for the struggling Internet company sign a non-disclosure agreement to access the company's financial data. The "no cross-talk" provision presents an obstacle to consortiums, and some potential bidders are said to be refusing to sign.

The no cross-talk provision aims to prevent all the interested parties from banding together, which could limit Yahoo!'s options down to one group buyer.

With a market cap of $20 billion, Yahoo! is considered too big to acquire except by the largest companies, such as Microsoft Corp., which forged a successful advertising partnership with the Sunnyvale, Calif.-based company after failing to acquire it in 2008 for $47.5 billion.

But even Microsoft is said to be teaming up to take on Yahoo! A group partnering the Redmond, Wash. software giant with private equity firm Silver Lake Partners and Canadian Pension Plan Investment Board is said to be in the works.

Given the complicated and close relationships among the bidders, Yahoo! may be wise in moving to prevent a cartel from forming.

Silver Lake, for example, is no stranger to group buy-outs, nor to Microsoft. The Menlo Park, Calif. firm led the consortium that bought Skype Technologies SA from eBay Inc. and two years later sold it to Microsoft for $8.5 billion -- four times what it paid.

Canadian Pension Plan is an investor in Silver Lake.

Other bidders for Yahoo! include private equity firms Providence Equity Partners LLC and Hellman & Friedman LLC. Also interested is Russian tech investor DST Global Solutions Ltd., which backs U.S. Internet companies, including Facebook Inc., Groupon Inc., Twitter Inc. and Zynga Inc. Jack Ma, CEO of Chinese Internet giant Alibaba Group Holding Ltd., 40% of which is owned by Yahoo!, has repeatedly expressed interest.

Last month, Silver Lake, DST and others partnered to announce a commitment to invest an undisclosed amount in Alibaba.