Project management firm John Laing's shares have risen sharply after it said it had received a takeover approach.
"The board confirms that it has received an approach...but emphasises that this approach is in very preliminary form," a statement said.
Shortly after the statement, Laing shares rose 16.3% to 341p, valuing the company at more than £815m ($1.4bn).
Laing owns and manages 48 private finance initiatives (PFIs) worth £335m and also owns Chiltern Railways.
In August, it said that road, hospital and school contracts helped lift half-year profits by £900,000 to £13.8m.