Updated from 12:41 p.m. EST

The latest round of rumors surrounding Sonus' ( SONS) books sent the stock plunging Tuesday before it staged a midday recovery.

Speculation on Wall Street centered on whether Steve Nill, the company's financial chief, had resigned amid an ongoing accounting problem and audit. The chatter sent the stock as much as 20% lower in late-morning trading before a midday rebound reclaimed most of that ground.

Sonus declined to comment on any aspect of the rumor.

Tuesday was only the latest case of the jitters for Sonus investors. Last month, the new-generation phone-switch maker was hammered in the stock market after disclosing that it had potentially misbooked sales. Sonus said then that an internal audit raised questions about the timing of some revenue, and that it had fired a few midlevel managers in connection with the snafu.

Last week, the company said it needed another two weeks to resolve its accounting inquiry and file its annual report.

Sonus was down 35 cents, or 7%, to $4.76 at around 12:30 p.m. EST.