Shares in Apple Computer fell by close to 2 per cent in midday trading on Thursday after the revelation that Steve Jobs, its chief executive, was handed 7.5m stock options in 2001 without the required authorisation from its board of directors.

The report in the Financial Times – based on information from people familiar with the matter – prompted a second day of selling, with $1.47 knocked off the share price by lunchtime, taking the shares to $80.05.

Records that purported to show a full board meeting had approved Mr Jobs’ remuneration, as required by Apple’s procedures, were later falsified. These are now among evidence being considered by the Securities and Exchange Commission as it decides whether to pursue a case against the company or any individuals over the affair

News of the irregularities, expected to be revealed in a regulatory filing by Apple shortly, will add to pressure growing on one of Silicon Valley’s most highly regarded companies since mid-2005.

Apple is among more than 160 companies to have admitted stock option backdating – handing options to executives and other employees at exercise prices that were set in hindsight at favourable levels.

The latest revelation is likely to add to questions about Apple’s internal investigation into the backdating issue. In October, it largely exonerated Mr Jobs, saying that while he had been “aware” of the backdating “in a few instances”, he “did not receive or otherwise benefit from these grants and was unaware of the accounting implications”.

Apple has refused to comment on the matter but said the company had handed the findings of its internal inquiry to the SEC.