The auction for Google's much-watched $3.3 billion (€2.67 billion) initial public offering (IPO) opened yesterday, despite the company saying a Playboy magazine interview with its founders may have violated Securities & Exchange Commission rules.

The disclosure, made in an amended offering document just hours before the auction opened, is the latest twist in the closely watched IPO and raised new questions as to how its unusual bidding process for shares will fare.

The company said it does not believe its involvement in the article constitutes a violation of the "quiet period" rules. However, it said it could be required to buy back the shares sold to investors in the IPO at the original purchase price for a period of one year following the violation.

Google opened its auction yesterday morning as expected, a person familiar with the auction confirmed. The group has filed to sell 25.7 million shares at an estimated price range of $108-$135 per share in a modified Dutch auction.

In a typical Dutch auction, the offering is launched at the highest price at which all of the shares offered can be sold to potential investors. But Google has left itself some wiggle room, saying it could price the IPO lower in order to get a wider distribution of its shares.

Google will announce the price of the IPO next week.

Google's auction is taking place during a difficult market for IPOs. With the broader equity markets under pressure and investor demand for new deals waning, a steady stream of IPOs has been postponed or withdrawn.