“It wouldn’t be a surprise if knowledge like this got passed along among executives and had a cascading effect through the community,” said James Post, a Boston University professor specializing in corporate governance and business ethics.

tencor scandal options backdating-5

Still, the manipulation elicited a public apology from Jobs and provoked the resignation of former Chief Financial Officer Fred Anderson from the company’s board. CEO Larry Ellison, who regularly describes Jobs as his best friend, served on Apple Computer Inc.’s board from 1997 until 2002 — a period that coincided with some of the company stock options now under review. Redwood Shores-based Oracle has said it has no backdating problems, but San Francisco-based Gap is among the companies revising its stock option accounting.

Cupertino-based Apple said it had “serious concerns” about how two former executives accounted for the company’s the stock options. And in 1999, Apple added retailing executive Millard “Mickey” Drexler to its board in 1999 and Jobs joined Drexler’s board at Gap Inc. Jobs left the Gap board in 2002 shortly after Drexler’s ouster as CEO in 2002, but Drexler remains on Apple’s board. Elson said conflicts of interest are even more likely to arise among directors when CEOs agree to serve on each other’s boards.

Silicon Valley business leaders have long served on each other’s boards, giving bright minds a way to share their collective wisdom and fostering a climate of corporate clubbiness that prizes personal networks as much as computer networks.

But what happens when bad ideas seep into chummy boardrooms?

The three directors — Chairman Giora Yaron, Igal Kohavi and Yair Shamir — have maintained they did nothing wrong and remained on Mercury’s board until the company’s recent $4.5 billion sale to Hewlett-Packard Co.

None of these three belonged to the boards of other companies embroiled in the scandal.

Citing the inquiries into its stock option accounting, Juniper turned down a request to interview Kriens, who became the company’s CEO a decade ago.

The fallout from stock option backdating has caused Juniper and Veri Sign to miss government-mandated deadlines for filing their quarterly financial statements — lapses that threaten to oust them from the Nasdaq Stock Market.

Reyes became the first prominent Silicon Valley leader to face criminal charges in the options imbroglio.

Reyes, who has pleaded not guilty, resigned from Veri Sign’s board two weeks after his July indictment on securities fraud and other charges.

No concrete evidence So far, there’s no concrete evidence to tie Silicon Valley’s stock option chicanery to the circle of directors who sat on common boards.