LONDON (Bloomberg) — Shares of British Airways Plc, Europe's third-largest carrier, rose 5.3 percent as Spain's Iberia Lineas Aereas de Espana SA agreed to open its books to a group including the London-based airline.Shares of British Airways rose 22 pence to 440.5 pence in London, giving the company a market value of $5.1 billion ($10.4bn). The stock is down 17 percent so far this year.

Iberia examined letters from a group including TPG Inc. and British Airways and will give more detailed information should a binding offer be made, the Madrid-based carrier said in regulatory filing yesterday. British Airways will make no additional investment in the Spanish carrier beyond the 10 percent it already holds as Iberia's biggest shareholder. "The fact Iberia is saying it will open its books if the TPG consortium makes a firm bid is likely have thrown a fresh light on BA's virtues," said Andrew Fitchie, an analyst at Collins Stewart in London. The stock was "cheap", he said.

Shares of British Airways rose 4.5 percent in May on speculation the airline might attract a private equity bid. There will be no private equity bid because the airline is not an attractive target for buyout firms, chief executive officer Willie Walsh said in May.

"A private equity bid simply cannot be excluded at this time," said Gert Zonneveld, an analyst with Panmure Gordon in London, with a "hold" recommendation on the stock.