Investors will be able to get their hands on Royal Mail shares today as full dealing in the company begins on the Stock Exchange.
Shares climbed further yesterday to value the company at almost £1.5 billion over its initial flotation price.
They hit a high of 475.3p in early trading - valuing the company at almost £4.8 billion, compared with its £3.3 billion initial valuation on Friday.
They settled back to 462p, a gain of about 1.5% on Friday's 455p close, as demand for the newly-privatised company shows no sign of easing.
At that level more than 700,000 small investors who bought stakes for an initial £750 will be sitting on a paper profit of about £300, assuming they did not cash them in on Friday.
And around 150,000 postal workers hold stakes worth more than £3,080 - although they cannot sell them for three years.
Shares in the company have now risen 40% above the 330p price the Government valued them at - stoking accusations the company was sold too cheaply.
The flotation was described by Labour leader Ed Miliband as a "fire sale of a great institution at a knock-down price".
Adrian Bailey, the Labour chair of the Commons Business Select Committee, said the early evidence of the share price "vindicated" concerns raised when it quizzed Business Secretary Vince Cable last week.
He added he would seek fresh hearings about the sell-off, including possible grillings of the banks which advised the Government on the firm's value, if the market price remained so high.
But he needs the agreement of the committee, which has a majority of coalition MPs.
"At the meeting last week it's fair to say that members of the committee had one view and the Secretary of State had another," he said.
"The share price movements have vindicated the concerns of the committee members.
"Let's see where the price settles."
Full dealing in the company's shares begins today, when all investors can buy and sell shares in Royal Mail. C onditional dealing started on Friday for investors who applied for shares through brokers.
That will be followed tomorrow by the result of a strike ballot by postal workers in the Communication Workers Union over issues linked to privatisation.
CWU members are expected to back industrial action, with any strike set to be held on or after October 23 - the run-up to the busy Christmas period.
Demand remained rampant yesterday, with about 16 million shares changing hands, following Friday's frenzy when more than 100 million shares were traded in the first hour.
Stockbroker Hargreaves Lansdown said it has been "very busy" again yesterday, after demand on Friday crashed its website and left phone lines jammed.
A spokesman for the Bristol-based broker said it is "controlling throughput" to its website - leaving some investors unable to trade online. But he said waiting times on its phone lines are down to less than a minute.
"If they cannot get through on the website they will be able to get through on the phones," he said.
Investors have been lured by the promise of healthy payouts, with Royal Mail shares expected to offer a dividend yield of around 4.3% based on yesterday's price.