Facebook Inc.'s initial public offering has triggeredallegations the social network and banks led by Morgan Stanleyselectively disclosed crucial information to investors. Securitieslaw experts say it's not clear the firms did anything wrong.

At issue is whether Facebook gave non-public, materialinformation to analysts that was then shared with select investorsin the form of lower earnings projections. The answer lies in theevidence uncovered and the interpretation of Regulation FD, a U.S.Securities Exchange and Commission rule that requires publicdisclosure of important information.

“This is a gray area,” Tamar Frankel, a professor at BostonUniversity School of Law, said in a telephone interview. “There area zillion rules, but there isn't a rule that addresses preciselythis.”