Groupon Inc. said in a regulatory filing on Friday that it plans to raise as much as $540 million in an initial public offering, less than previously planned, as the largest daily deals company grapples with a weak equity market, executive departures and questions about its accounting and business model.

Groupon plans to sell 30 million shares at between $16 and $18 each, the filing said. That means the company aims to raise $480 million to $540 million from the IPO, depending on investor demand.

Groupon is set to launch a roadshow next week to persuade potential investors to buy stock in the offering. Chief Executive Andrew Mason, Chief Financial Officer Jason Child and Jeff Holden, head of product at Groupon, will be speaking during the roadshow.

Groupon in June filed to raise $750 million in its IPO, but equity markets have fallen and become a lot more volatile since then.

The company changed its accounting twice under pressure from investors and regulators. It also lost two chief operating officers this year, and some analysts have questioned the long-term viability of its business.

These challenges have made the Groupon share sale the most closely watched IPO in recent years. If the offering succeeds, it bodes well for other companies that are also considering going public, such as social gaming giant Zynga and Facebook, the largest social network. If Groupon struggles out of the gate, other IPOs may be delayed or pulled.

(Reporting by Alistair Barr, editing by Bernard Orr)