WARWICK, Bermuda (Reuters) - Billionaire Joseph Lewis disclosed in a regulatory filing on Wednesday that he has increased his stake in hard-hit investment bank Bear Stearns Cos (BSC.N: Quote, Profile, Research) to 9.57 percent.



Lewis, who made his fortune trading currencies, has been building his stake in Bear Stearns over the past few months. In September, he paid $860.4 million for a 7 percent stake which he then increased to 8.01 percent earlier this month.



Lewis, a reclusive Englishman who splits his time between homes in Florida and the Bahamas, is Bear Stearns largest shareholder, according to Reuters Data.



The latest filing with the U.S. Securities and Exchange Commission showed that Lewis' funds bought shares from Dec. 6 through Dec. 21 at prices varying from $89.08 to $110.00.



Lewis and several investment vehicles he controls paid a total of $1.19 billion for the stake, the filing said. He paid an average of $101.07 per share in his latest foray.



Based on Bear's closing share price of $88.80 on Monday, Lewis' stake is worth about $985.68 million, leaving him down roughly $200 million.



Shares have fallen roughly 17 percent since Lewis first announced he had built a stake in the company in September.



Since the beginning of the year, Bear Stearns shares have plunged more than 45 percent as the slumping mortgage market hurt the bank's biggest businesses and prompted write-downs on mortgage-related assets. Bear also suffered a hit to its reputation as a savvy bond trader in July when two mortgage hedge funds it managed were forced into bankruptcy.