Guide · Markets
Insurance Float Explained: How Insurers Invest Premiums
Insurance float is the money an insurer holds between collecting premiums and paying claims, and invests in the meantime. Berkshire's was about $177.5 billion in June 2026.
On Saturday, November 7, 2026, Berkshire Hathaway reported that its after-tax insurance underwriting profit fell 43% in the third quarter to $1.352 billion, and that investment income from its insurers fell 14% to $2.734 billion. Those two lines are the two halves of every insurance business, and the money that connects them has a name: float. At the end of June, Berkshire's float was about $177.5 billion, according to its second-quarter release, equal to almost half of the $377.4 billion it reported in cash and Treasury bills at the end of September.
Float exists because insurers are paid first and pay later. A driver buys a year of car insurance today; the claim from an accident in March may be settled months afterwards, and a liability or workers' compensation claim can take years. In the meantime the insurer holds the premiums. Float is roughly the total of those funds: unearned premiums plus reserves for losses that have occurred but not yet been paid, minus amounts still owed by agents and policyholders and some prepaid costs. The insurer does not own this money, but it can invest it until the claims come due.
Whether float is valuable depends on underwriting. If premiums exceed claims and expenses, the insurer makes an underwriting profit and the float costs less than nothing: it is paid to hold other people's money. If claims and costs exceed premiums, the underwriting loss is the cost of the float, like an interest rate. The usual measure is the combined ratio, claims plus expenses divided by premiums earned: below 100% is an underwriting profit, above 100% a loss. An insurer with a 97% combined ratio has borrowed its float at minus 3%; one at 105% is paying 5%.
Berkshire's third quarter shows how quickly that cost can move. GEICO, its car insurer, made a pre-tax underwriting profit of $982 million, against $1.773 billion a year earlier, as losses and underwriting expenses rose. The float itself barely changes from one quarter to the next, so the investment income it earns depends on interest rates and how the money is invested; for an insurer that keeps much of its money in Treasury bills, as Berkshire does, changes in short-term yields feed straight into that line.
Float also explains why insurers are sensitive to things that seem unrelated. Higher interest rates raise the income earned on the same pool of money, so insurers often benefit when rates rise. Inflation in car repairs, medical costs or court awards raises claims, so reserves set aside last year can prove too small and must be topped up, which hits underwriting profit. And a large disaster can force an insurer to sell investments at a bad time, which is why insurers that write catastrophe cover keep more of their float in liquid assets.
Three checks help when an insurer reports. Look at the combined ratio, not only profit, to see whether the float is costing anything. Look for reserve development, the changes to estimates for claims from earlier years: favourable development flatters the current year, adverse development is a warning. And compare investment income with the size of the float to see what yield the insurer earns on it. Berkshire's November report scored worse on the first and the third, which is why its operating earnings fell even as its railroad and utilities grew.