# Reserves, reinsurance, and float: the hidden financial machine
A hurricane forms in the Atlantic. Before it makes landfall, insurers are already doing math. The moment a policyholder pays a premium, the insurer collects cash it may not pay out for months or years. That gap, between money in and claims out, is where the real business lives.
Warren Buffett has said for decades that Berkshire Hathaway's insurance operations are its engine, not because of underwriting profit, but because of the money they hold in the meantime. Let's dissect how that works.
An insurer runs on three interlocking mechanisms:
1. Reserves: money set aside today to pay future claims.
2. Reinsurance: insurance for insurers, used to offload large or concentrated risks.
3. Float: premiums collected but not yet paid out, which the insurer invests in the meantime.
Follow one hurricane season and you can see all three fire at once.
When you sell a policy, you take on a liability (a future obligation to pay). You do not know the exact amount or timing, so you estimate it. That estimate is a reserve.
There are two main kinds:
Reserves directly shape reported profit. Set them too low and you flatter today's earnings while hiding tomorrow's losses. Set them too high and you understate profit and tie up capital.
Regulators watch this closely because under-reserving is a classic path to insurer insolvency. In the United States, statutory reserves follow rules overseen by state regulators and coordinated through the National Association of Insurance Commissioners.
Concrete example. An insurer books 500 million dollars in hurricane reserves in the fourth quarter. Over the next two years, actual claims come in lower. The insurer releases the excess reserve, which shows up as profit later. This is called reserve development, and analysts scrutinize it to judge whether management is being honest or aggressive.
No single insurer wants full exposure to a Category 5 hurricane hitting a dense coastline. One event could wipe out years of profit. So they buy reinsurance: they pay a premium to a reinsurer, who agrees to cover part of the losses.
The insurer that buys protection is the cedant. Passing risk along is called ceding.
Some risk gets passed even further, to capital markets. A catastrophe bond (cat bond) lets investors earn attractive interest, but if a defined disaster occurs (say, a hurricane above a certain wind speed hitting a certain region), investors lose part or all of their principal, and that money pays claims.
Cat bonds let insurers tap far more capital than traditional reinsurers alone can supply. The market has grown substantially over the past decade, though exact size figures vary by source and year.
Why cede at all? Because smoothing losses is worth paying for. A cedant trades some expected profit for a much narrower range of outcomes. That stability protects its credit rating, its regulatory capital, and its ability to keep writing new business after a bad year.
Here is the mechanism Buffett prizes. Between collecting a premium and paying a claim, the insurer holds cash. Across millions of policies, that pile is enormous and surprisingly stable, because as old claims are paid, new premiums flow in.
That pool is float.
The insurer gets to invest float and keep the investment income. In effect, policyholders lend the insurer money, and sometimes the insurer gets paid to hold it.
The magic number is the combined ratio:
Combined ratio = (Losses + Loss adjustment expenses + Underwriting expenses) / Premiums earned
Below 100% = underwriting profit (you were paid to hold float)
Above 100% = underwriting loss (float has a cost)If the combined ratio is 97 percent, the insurer earns a 3 percent profit on premiums before any investment income. On top of that, it invests the float. That is two profit engines stacked.
Even at a combined ratio slightly above 100 percent, an insurer can still come out ahead if investment returns on float exceed the small underwriting loss. This is why Buffett describes good float as better than free money.
Float is not truly the insurer's money. It must be available to pay claims. So insurers generally invest float conservatively, heavily in bonds, to match the timing of expected payouts. This is called asset liability matching.
Chase yield too aggressively and you risk having to sell assets at a loss right when a catastrophe demands cash. The 2008 financial crisis showed what happens when insurers stretch too far on the investment side.
Vérification des acquis
1. According to the lesson, why does Warren Buffett consider insurance operations the 'engine' of Berkshire Hathaway?
2. What is the key conceptual distinction between a case reserve and IBNR?
3. Why do regulators scrutinize under-reserving so heavily?
4. Select ALL correct answers about how reserve estimation affects an insurer's financials.
Sélectionnez toutes les réponses correctes.
5. Select ALL correct answers describing the three interlocking mechanisms an insurer runs on.
Sélectionnez toutes les réponses correctes.
Watch the machine run end to end.
Before the season. The insurer has collected premiums all year. It holds billions in float, mostly in high-quality bonds earning interest. It has already bought excess-of-loss reinsurance: it retains the first 100 million dollars of catastrophe losses, reinsurers cover the next tranche, and a cat bond sits above that.
Landfall. A major hurricane hits. Damage estimates start rolling in.
Reserving. Within days, actuaries book a large reserve: case reserves for reported claims plus a big IBNR estimate for damage not yet reported. Reported profit for the quarter drops sharply, even though most cash has not left yet.
Recovery from reinsurers. As losses climb past the 100 million dollar retention, the insurer files claims with its reinsurers. It records a reinsurance recoverable, an asset representing money owed by reinsurers. Net losses to the insurer are far smaller than gross losses.
Paying claims over time. Claims pay out over months and years. Float shrinks as cash leaves, but new premiums keep refilling it.
Reserve development. A year later, if actual claims land below the reserve, the insurer releases the excess, boosting later profit. If claims run high, it strengthens reserves, hurting profit.
The result: a single catastrophe is absorbed without sinking the company, because reserves anticipated it, reinsurance capped it, and float generated income throughout.