Insurance companies earn investment profits on "float". Float, or available reserve, is the amount of money on hand at any given moment that an insurer has collected in insurance premiums but has not paid out in claims. Insurers start investing insurance premiums as soon as they are collected and continue to earn interest or other income on them until claims are paid out. The Association of British Insurers (grouping together 400 insurance companies and 94% of UK insurance services) has almost 20% of the investments in the London Stock Exchange. In 2007, U.S. industry profits from float totaled $58 billion. In a 2009 letter to investors, Warren Buffett wrote, "we were "paid" $2.8 billion to hold our float in 2008".