Profit for Royal Mail investors as shares soar to a new high on the stock market David Jones of City spread better IG Index said: "It looks lke lots of smaller investors selling, but the bigger institutions who missed out are continuing are still buying." If the Royal Mail shares hit 500p, 51 per cent above the privatisation price, investors would be sitting on a profit of £385. The price rise will pile even more pressure onto the Government after it emerged last night the Business, Innovation and Skills select committee want to investigate why Royal Mail was sold off so cheaply. The Government was also coming fire today from investors who said they were still waiting for details of how to sell, while those lucky enough to be given a reference number could not through to the Helpline to trade. On Twitter Paul Harmston wrote: "It's a shambles." Another Jessica Brown said: "No reference no, phone lines jammed and they have all our cash. Why don't we have our reference numbers? Nearly 700,000 small investors were each given 227 shares under the privatisation, valued at £749.10. At the time, analysts said Royal Mail was under-valued by as much as £1 billion. Mario Dunn of the Save Our Royal Mail campaign said: "The share price today is proof positive that the Government chronically undervalued Royal Mail. This is larceny on a grand scale. Vince Cable has the temerity to call the matter "froth." If Mr Cable thinks ripping the taxpayer off by a billion pounds is "froth" then he is not fit for office. Mr Cable should do the decent thing and resign. Michael Fallon, the Business minister, and Moya Greene, Royal Mail chief executive, marked the postal operator's official stock market listing by appearing at the London Stock Exchange this morning. Gert Zonneveld, the co-head of research of stockbroker Panmure Gordon, said the share price was likely to remain around the current high levels because of demand from the hundreds of fund managers and stockbrokers who missed out on shares last week. He said: "The one thing that supports the share price is that so many institutions need to get exposure to this company. If the market value stays above £3.8 billion, it's going into the FTSE 100 and many tracker funds and long-only funds will want to have exposure to it. Only 300 out of 800 institutions got shares last week so they will have to go in the market too. He added that the regulatory regime governing Royal Mail was far more favourable than in previous years and was only likely to add further support to the share price. Fund manager Hargreaves Lansdown, whose website crashed under the volume of "sell" orders on Friday, was forced to suspend the website briefly again yesterday to process the backlog of requests from clients. A Government official said at the weekend that ministers would be reviewing glitches at the company.