Updated from March 30 The Financial Accounting Standards Board returns this week to a battlefield where it was vanquished and left for dead 10 years ago, hoping to revive support for a proposal that would put the cost of stock options in the plain sight of investors on corporate earnings statements. The new proposal, expected as early as Tuesday, is a blow to Silicon Valley, which has fought such regulations for years while continuing its practice of awarding generous options to employees and, especially, top executives. The new rule from the nation's lead accounting body would force that practice into the open, with unforeseen and potentially far-reaching implications on corporate practices and share prices. (On Wednesday, FASB formally released a draft of the new rule, which is now opened for public comment. The accounting group expects to issue a final rule this fall.) Granted, public companies already disclose the hypothetical cost of options expensing in the footnotes of quarterly reports filed with the Securities and Exchange Commission. Furthermore, the FASB proposal is widely anticipated and many firms have already adjusted their accounting in anticipation. On Monday, for example, Circuit City ( CC) announced it will expense stock options beginning with its fourth-quarter report this week. "It will not very likely have an effect on stock prices at this point," Meir Statman, chair of the finance department at Santa Clara University, said of the FASB ruling. Under efficient markets theory -- which postulates that current prices accurately reflect the knowledge and expectations of all investors -- expensing options should be a nonissue because the information is already available, agreed Ken Broad, a portfolio manager at Transamerica Investment Management. "But that begs the question why the tech industry has fought tooth and nail against it," said Broad, who believes expensing options will ultimately produce a gradual decline in tech industry shares. Of course, the market does not always value stocks in a rational way. "Stocks will probably trade on price-to-earning ratios and the last headline and which broker screams the loudest," said David Blitzer, chief economist at Standard & Poor's. "That's what they'll trade on the day after the FASB" rules go into effect.