HBOS, Britain's biggest mortgage lender, unveiled a 4 billion pound ($7.9 billion) rights issue to rebuild its capital base after a hefty hit on the valuation of risky assets, Reuters reported. HBOS will offer two new shares for every five at 275 pence per share, a 45 percent discount to Monday's close of 495.75p, it said on Tuesday. The bank said it took negative fair value adjustments in the year to date of 970 million pounds in the trading book and 1.87 billion pounds, post tax, in the banking book. The bank said it would reduce its dividend payout ratio to 40 percent, with the interim 2008 dividend to be paid in shares. The final dividend for the year, however, is set to be paid in cash.