The Combined Ratio Separates Underwriting Skill From Market Luck
An insurance company has two ways to make money and only one of them reflects skill. The combined ratio separates them in a single number.
The Two Engines
An insurer earns from underwriting, which is collecting more in premiums than it pays out in claims and expenses, and from investment income on the money it holds between collecting premiums and paying claims.
Both are real. Only the first reflects whether the company is good at its actual job, which is estimating risk and charging correctly for it.
An insurer can lose money on every policy it writes and still report profits if markets are generous. That is not a durable business, and the combined ratio is the number that exposes it.
The Calculation
The combined ratio is the loss ratio plus the expense ratio.
The loss ratio is claims paid and reserved, divided by premiums earned. The expense ratio is the cost of running the business, including commissions to brokers, divided by premiums.
A combined ratio of 96 means that for every 100 dollars of premium, 96 went to claims and expenses, leaving 4 dollars of underwriting profit before any investment return.
Below 100 means the company is paid to hold other people's money. Above 100 means it is paying for the privilege, and the investment portfolio has to make up the difference.
Why Above 100 Is Not Automatically Failure
An insurer collects premium now and pays claims later, sometimes years later for long tail lines such as liability. In the interim it invests that money, which is the float.
If float can be invested at attractive rates, a combined ratio slightly above 100 can still produce an acceptable overall return. This is why underwriting discipline historically loosened when interest rates were high: investment income covered sloppy pricing.
When rates are low, that cushion disappears and the industry is forced back toward underwriting discipline. The relationship between rate levels and pricing discipline is one of the more reliable patterns in the sector.
The Underwriting Cycle
| Phase | Pricing | Combined ratio |
|---|---|---|
| Soft market | Competitive, falling | Deteriorating |
| Losses emerge | Capital withdraws | Poor |
| Hard market | Rising sharply | Improving |
| Capital returns | Competition resumes | Deteriorating again |
The cycle repeats because capital chases good returns into the sector, competes prices down, and produces the losses that drive it out again. A catastrophe that destroys industry capital is, counterintuitively, good news for the survivors, because it removes competing capacity and lets prices rise.
Reserves Are Where Judgement Lives
The loss ratio depends on reserves for claims that have occurred but are not yet settled, and on estimates for claims incurred but not yet reported.
Those are estimates, which means they are a judgement the company makes about its own performance. An insurer under pressure can set reserves optimistically, reporting a better combined ratio now and taking the shortfall later.
The disclosure that matters is reserve development: whether prior year reserves proved sufficient. Consistent favourable development suggests conservative reserving. Repeated adverse development means the company has been reporting profits it did not earn, and the reckoning arrives in later periods.
What Good Looks Like
A consistently strong underwriter runs a combined ratio below 100 across a full cycle, including years with catastrophes, and shows favourable reserve development. It grows premiums when pricing is attractive and lets business go when it is not, which means its premium growth should look erratic rather than steady.
An insurer growing premiums smoothly through a soft market is winning business on price, and the claims arrive later.
The Bottom Line
The combined ratio separates underwriting skill from investment luck. Below 100 the insurer is paid to hold float, above 100 it is buying float with underwriting losses. Read it across a full cycle, alongside reserve development, and treat steady premium growth in a soft market as a warning rather than a sign of quality.