United lodged their intention to sell 10.2% of the club on Monday evening.
It is intended the sale will raise around £150million for the owners, although there have previously been suggestions that interest in the sale has been lukewarm.
However, what has really angered the Manchester United Supporters Trust is that previously, the Glazer family had indicated they would use all the proceeds to reduce the club's debt, which presently stands at £437million.
Now it appears only half the money will be used for that purpose, with the rest remaining with the family.
The Glazers themselves have been silent on their intentions.
United have confirmed restrictions placed on it by the Securities and Exchange Commission in the US prevent it commenting on anything to do with the filing until such time as the shares are being traded.
MUST chief executive Duncan Drasdo has filled the void with his own damning assessment of the situation.
"Supporters are going to be very angry about this," he said.
"The Glazers have already cost United more than £550million in debt-related fees and now another slap in the face as they help themselves to half of the proposed IPO proceeds.
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"Each of the six lineal descendants of Malcolm Glazer will claw out US dollars 25 million for themselves.
"Clearly this has nothing to do with benefits for Manchester United.
"What is the sudden reason for this desperation for cash now?"
MUST are unlikely to ever get an answer to that particular question, nor questions that have been raised by critics about whether chief executive David Gill and manager Sir Alex Ferguson are to profit directly from the IPO.
"There is now no doubt that this IPO is bad for Manchester United supporters, Manchester United Football Club and any investors gullible enough to pay the inflated price they've attached to inferior shares which have just 1/10 of the voting rights of the Glazers shares and no dividends," said Drasdo.
"Their bare faced cheek is almost unbelievable."
Supporter sentiment has never been a significant influence on the Glazer family's thinking.
Monday's announcement came just hours after it was confirmed a massive new shirt sponsorship deal with US car giant Chevrolet had been agreed, which will take effect from 2014.
That deal will eventually swell the Red Devils' growing commercial income still further.
However, critics will also point to the fact the club are yet to post end-of-year accounts which show the exact amount bowing out of the Champions League group stage cost them.