Manchester United's controversial flotation in New York continues to provoke an angry reaction from supporters after it emerged that senior employees at Old Trafford stand to benefit from a share scheme worth up to $320m (£204m).

A highly lucrative "2012 Equity Incentive Award Plan", as it is described in the Initial Public Offering (IPO) prospectus released on Monday, has raised questions among some United fans as to whether Sir Alex Ferguson, the manager, and David Gill, the chief executive, will stand to personally profit from the Glazers' decision to list the club on the New York stock exchange.

United are refusing to comment on the situation. "Under the regulations of the SEC [Securities and Exchange Commission], we are not permitted to disclose the contents of the document," said a United spokesman.

The Glazers, who are looking to raise up to $383m (£244m) by selling more than 19m shares in the Premier League club at up to $20 a piece, came in for severe criticism on Monday when it transpired they had reneged on their promise to use all the funds from a successful flotation to reduce United's £437m debts.

Ferguson and Gill have both staunchly defended the American owners in the past, much to the dismay of those that have protested against the way that the club has been run since the Glazers' leveraged buyout in 2005. Only nine days ago, Ferguson described the Glazers as "great" and suggested that "the majority of real fans will look at it realistically and say it's not affecting the team". Those remarks went down badly with some supporters.

Doubts also persist about how successful the IPO will prove to be, and the Equity Incentive Award Plan already looks like being a controversial element. According to the club's prospectus, United's executive committee, including Gill, are in line for a £1.25m IPO bonus once the deal is done. But the richest rewards will go to those selected to take part in the Equity Incentive Award Plan.

The plan is designed to "attract, retain and motivate selected employees, consultants and non-employee directors", according to the prospectus. Some 16m shares – worth a potential $320m at the top end of the forecast IPO price – will be set aside for those selected to be part of the plan. The awards will be made using a variety of schemes and if the company is taken over, a "change of control" clause will allow United to pay out the share awards immediately.

Andy Green, a financial analyst who writes the "andersred blog" on football ownership and is an adviser to the Manchester United Supporters Trust (Must), said United should clear up Ferguson's situation. "I'm not sure you can have a $288m [the mid-range valuation] benefit package for key employees and not include the manager," Green said. "I think he should probably come and tell the fans either way. If he's not benefited, fair enough. But it's certainly going to be something that's on a lot of people's minds."

Green also believes Ferguson is on dangerous ground with his comments about the fans in relation to the Glazers. "I think he is risking tarnishing some of his legacy, which is a great shame because he is the greatest manager probably in English football history. But his association with all this skulduggery is sad. Also, he has rejected the fans who are understandably and correctly concerned about what is going on. Look at this IPO, it was promised to pay down the debt. It's now making hardly any impact – it's the owners taking money out and leaving the club in debt. Being concerned about that is perfectly legitimate. And then for him to say that you're not a real fan if you are concerned … well, that's quite staggering."

Duncan Drasdo, the Must chief executive, is aware of fans' concerns but said that he wants to keep the spotlight on the Glazers for the moment. "I know people are asking if David Gill and Sir Alex Ferguson are going to benefit from the IPO and whether that has affected their statements. But I don't want to divert attention away from the terms of the IPO and the pressure we're trying to put on the banks."