Float as Investable Capital

Definition

Float is "the funds of others that insurers, in the conduct of their business, temporarily hold" — money collected as premium today against claims that won't be paid until later, sometimes years or decades later. Because it's available to invest in the interim, an insurer can absorb an underwriting loss (paying out more in claims and expenses than it collected in premium) and still come out ahead overall, so long as the investment return on the float covers the gap. When underwriting itself is profitable, the float is effectively better than free — Buffett describes being paid to hold other people's money.

In the Book

Buffett develops float's mechanics through the contrast between insurance lines. Crop-hail insurance generates almost no float — premiums are paid right before the risk window and claims settle almost immediately, so a combined ratio of exactly 100 yields no profit at all. Malpractice and other "long-tail" liability lines are the opposite: claims surface years after the policy is written and settle only after prolonged litigation, so insurers hold large sums for extended periods, and a combined ratio of 115 or even higher can still be profitable once investment income on the float is counted. He also warns this cuts both ways — long-tail business that looks like it will settle at a 115 combined ratio can later "smack the insurer with 200, 300 or worse" once all claims are finally paid, which is why he insists on pricing with a wide margin of safety rather than targeting breakeven combined ratios. Berkshire's insurance operations (GEICO, National Indemnity, and later the reinsurance business) are run explicitly to grow float per dollar of premium, treating the float itself as the asset being acquired.

Why It Matters

Float reframes a business's liabilities — money it owes but hasn't yet paid out — as a source of investable capital rather than pure cost, so long as what's collected exceeds, over time, what's eventually paid. The same structural insight applies wherever an organization holds funds, obligations, or resources ahead of when they must be delivered: subscription revenue collected before service is rendered, deposits held before withdrawal, deferred maintenance funded before it comes due. Recognizing float turns "how much do we owe" into a two-part question — how much, and for how long — and the second half is where the leverage lives.