The London Stock Exchange opened almost two hours late on Friday as a technical issue delayed trading in the City's top shares.
Due to open at 8am as usual, trading in FTSE 100 and FTSE 250 companies could not start until 9.40am while a potential trading services issue was being investigated.
The FTSE 100 initially jumped 57 points, or 0.8% upon opening. It followed two days of heavy losses for the index amid growing fears of a global recession and a rebound in the value of the pound.
Analysts had been expecting London stocks to open higher after those in the US and China made gains overnight.
Traders were kept waiting until just after 9.15am for confirmation of when the market would open, but the LSE provided updates in the meantime.
Shares in smaller companies on the FTSE 350 and junior market Aim continued to trade.
The last time the London open was held back was June 9 last year, when it was delayed by an hour until 9am due to a technical glitch.
Neil Wilson, chief market analyst at Markets.com, said: "These things happen - the last delayed start to trading was only a year ago. Technical glitches are inevitable, frustrating as it is for everyone."
Craig Erlam, senior market analyst at Oanda, said: "Unfortunately I don't think we can blame Brexit for this one but maybe I'll be proven wrong."
No further details on the problem have been released by the LSE.
Meanwhile sterling was trading 0.4% higher on the US dollar on Friday morning, extending its gains from the previous day.
