Reserves, reinsurance, and float: the hidden financial machine

# 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.

The three moving parts

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.

Reserves: the promise on the balance sheet

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:

• Case reserves: estimates for claims that have already been reported. A homeowner files a roof claim; the adjuster pegs it at, say, 40,000 dollars. That figure becomes a case reserve.
• IBNR (Incurred But Not Reported): claims that have happened but the insurer does not know about yet. After a hurricane, thousands of damaged homes exist before the calls come in. Actuaries estimate this bulk using historical patterns.

Why reserves matter so much

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.

Reinsurance: passing the hot potato

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.

Two common structures

• Proportional (quota share): the reinsurer takes a fixed percentage of premiums and losses. If a reinsurer takes 30 percent quota share, it collects 30 percent of premiums and pays 30 percent of claims.
• Non-proportional (excess of loss): the reinsurer pays only above a threshold. Example: the cedant keeps the first 100 million dollars of catastrophe losses (its retention), and the reinsurer covers the next 400 million. This is the workhorse structure for catastrophe risk.

Catastrophe bonds

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.

Float: the money in between

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.

Why float is powerful

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.

The catch

Float is not the insurer's money to keep. 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.

Putting it together: one hurricane season

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.

Why this shapes the whole industry

• Pricing depends on reinsurance cost. When reinsurers raise rates (a hard market), primary insurers pass those costs to customers or pull back from risky regions. After heavy catastrophe years, coastal homeowners often see steep premium hikes or find fewer insurers willing to write policies.
• Low interest rates squeeze float. When bond yields are low, float earns less, so insurers must underwrite more profitably to compensate. Rising rates in the 2020s improved investment income for many insurers.
• Reserves are a judgment call. Two honest actuaries can produce different reserve estimates. This is why reserve adequacy is a top focus for regulators, rating agencies, and investors.

Key Takeaways

• Reserves are estimates, not facts. They set aside money for future claims (case reserves for known claims, IBNR for unknown ones) and directly drive reported profit.
• Reinsurance caps the downside. By ceding risk through quota share, excess of loss, or cat bonds, insurers trade some profit for survivable outcomes after catastrophes.
• Float is the hidden engine. Premiums held before claims are paid can be invested, giving insurers a second profit source on top of underwriting.
• The combined ratio is the scorecard. Below 100 percent means you are paid to hold float; above 100 percent means float has a cost that investment income must cover.
• Match assets to liabilities. Float must stay liquid enough to pay claims, so conservative, timing-matched investing protects the whole machine.