The Port Macquarie man joined the throng to what's been touted as the biggest float of a public asset since Telstra.

But he was one of a number of small investors who were aggrieved that they could not cash in on "stag" first-day profits in the same way as institutional banks and shareholders that had used a broker.

"It's not really even-stevens. I would think most would be thinking they might sell on Tuesday," he said. "I think it's been a bit haphazard. This is the biggest float this side of Telstra."

Medibank shares ended 7 per cent higher for retail investors on their debut but many who wanted to lock in a profit on day one were left confused and angry after they discovered they'd have to wait more than a week to trade their stock. 

Derek Darby, a retail investor from Melbourne, said he received an email accepting his application but it arrived in his inbox 25 minutes after the company floated at midday.

"I was told if we'd been allocated shares through a broker firm offer, then we could transact, but as we made the application as policyholders, we would have to wait till December 1," he said.

When Fairfax Media spoke with the Medibank share offer hotline it confirmed that any retail investor who applied through a broker would have received a holder identification number (HIN) by Tuesday morning, which allowed them to sell their shares. But those that applied as a member of the general public would have to wait.

Mr Darby also contacted E-Trade and Westpac and was told they were manually adding allotted shareholdings to their system, provided investors could fax through the paperwork. This would allow them to transact on a deferred basis.

Commsec customers were sent an email on Tuesday saying that those who had applied through the Medibank general public offer "may be able to trade provided we can verify your holdings".

It said investors would be able to trade online from next Tuesday.

David Jackson, a Killara -based retiree, said he thought he'd snapped up about $10,000 of the shares for his self-managed super fund – about 20 per cent of his order.

"It was touch and go whether we did try and invest in it or not, because the price was always going to be fairly high," he said.

Mr Jackson wasn't sure of his strategy with his new holding. "Whether or not I continue to hold them, I haven't decided yet. I'll see how it flows, and if it goes up at a ridiculous price I think I should sell," he said.

"It's only $10,000 so it's not going to be a major part of the portfolio, and I may decide to sell anyway to clear it up and move onto something else."