Swansea Supporters Trust has yet to see evidence that the group looking to take a controlling interest in the Swans has money in place to invest in the club, says the trust's vice chairman.
Jim White told BBC Radio Wales: "This is a sale of shares, there's no other way to describe it at the moment.
"The reality is we have not seen any details of investment."
Ex-Swans assistant boss Colin Pascoe said the club have been "frightened" into seeking new investors.
The Swans hope an agreement, reported to be worth up to £100m, will be reached in a matter of weeks.
"We believe we have a proposal which helps Swansea progress both on and off the field," said chairman Huw Jenkins.
Frightened by relegation battle
Pascoe, who was also assistant boss to Brendan Rodgers at Liverpool, worked under American owners at Anfield.
"It would have been a massive decision for Huw Jenkins to take to sell, they [the board] have achieved so much," Pascoe told BBC Radio Wales.
"But to compete in the Premier League, you need the money, everything is inflated.
"This year may have frightened Swansea, things haven't gone right on the pitch.
"Maybe they feel they don't want to be in this position again, so they need investment."
Lack of information
However, the supporters trust's White feels a lack of information means it is unclear whether the move would lead to increased spending power for the 2013 League Cup winners, who have been linked to overseas investment before.
"We have not been party - and are disappointed about that - to the same level of information as other shareholders have had, but from what we have seen, this is a share sale," he added.
"We know the club needs to move forward, the trust is not against investment, we know the club needs to move on and progress.
"But we have not seen any details or further information around investment as such.
"No one doubts investment is needed, but look at Leicester City - they have a similar wage bill to what we at the Swans have.
"They have shown you can compete without billions of pounds."
The Trust currently own a 21% stake in the club.
White says the trust wants to be reassured that they are not going to be squeezed out of the club in the long term.
"What we understand is the new owners are looking for a 75.1% share in the club and in the UK, under company law, when you get to that, then you can start to make other decisions that hold sway over other shareholders," he explained.
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"So I guess we are looking for assurances. For example, what could happen, is any new owners could continue to issue new shares.
"If they were to do that and the trust, as the major share holder left in that case, couldn't match that investment, the trust could be diluted and eventually diluted pretty much out of existence.
"That is the type of condition we are looking to prevent in any agreement with the new owners and that's the kind of thing we are looking to get protection on."