RLI or White Mountains: which insurance stock to buy?
2026-07-15 · By Lubin Danilo, founder of Lubin Investment
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RLI and White Mountains each score 9 out of 10 in my quality screen, but they are not the same business: RLI underwrites specialty risks directly, White Mountains is a holding company that owns stakes in several insurers and asset managers. Both trade well below my estimated reasonable buy price. Here is why, and what really sets them apart.
Two different ways of doing insurance
When you picture an insurance stock, you usually imagine one thing: a company that sells policies, collects premiums, and pays claims. That is exactly RLI's business. White Mountains barely sells any policies directly. It is a holding company, a structure that owns stakes in several insurance and asset management businesses rather than running a single line of business itself. Two models, two ways of making money, and yet both score 9 out of 10 in my quality screen.
Before comparing numbers, it helps to understand what each company actually owns, because the word insurance covers two very different economic realities here.
RLI: the specialist that picks its risks
RLI Corp underwrites in the so-called E&S (excess and surplus lines) market, a roughly $300 billion segment of US insurance where insurers can set their own terms and pricing, unlike the standard admitted market where rates are regulated state by state. In practice, these are risks too unusual, too volatile, or too specific for generalist insurers: a construction crane, a sporting event, a restaurant franchise with an unusual claims history. RLI ranks among the top 20 players in this market, with $848 million in gross E&S premiums in 2024, 42% of its total volume.
My screen gives it 9 out of 10. The most telling number: in the first quarter of 2026, RLI posted a combined ratio of 88.4%. This ratio measures claims paid plus operating expenses, relative to premiums collected: below 100%, the insurer makes money on underwriting itself, before even putting premium money to work while waiting to pay claims. At 88.4%, RLI keeps about 11.6 cents of pure underwriting profit for every premium dollar, a level few generalist insurers sustain over time.
RLI's weak spot: a market that is turning
The one criterion that fails in my screen for RLI is margin expansion: margins are compressing rather than widening. This is not an execution problem, it is the sector cycle turning. After several years of rising rates (a hard market), the property and casualty insurance sector is entering the opposite phase, a soft market: competition between insurers is pushing prices down on some lines, particularly property insurance. RLI itself confirmed this by cutting its 2026 catastrophe reinsurance program by $150 million, citing exactly these softer conditions.
One reassuring signal offsets this cyclical risk: in February 2026, rating agency AM Best upgraded all of RLI's subsidiaries to A++ (Superior), its highest rating. That is a sign of a balance sheet judged solid by an independent outside evaluator, even in a market becoming more competitive.
White Mountains: the compounder that owns pieces of insurers
White Mountains works the other way around. It is a compounder: a company that grows its capital year after year by buying, building up, and sometimes selling stakes, rather than running a single book of policies itself. Its current portfolio includes Ark Insurance (a Bermuda-based insurer and reinsurer active in natural catastrophe risk), Kudu Investment Management (which takes minority stakes in asset management firms), and until recently NSM Insurance Group, a specialty US broker.
The most important news on this name: White Mountains has signed a definitive agreement to sell NSM Insurance Group to funds affiliated with Carlyle for $1.775 billion. Against White Mountains's total market cap of roughly $5 billion, that is a sale representing more than a third of the company's value in a single transaction. This kind of cycle, buy a business, build it up over several years, then sell it to a buyer willing to pay a good price, is exactly the mechanism by which a compounder creates value over time: the capital freed up by the sale can then be redeployed into new stakes or returned to shareholders.
White Mountains's weak spot: profit that is not all cash
The criterion that fails for White Mountains in my screen is cash conversion of earnings, at 0.58 (below the level I consider healthy). This is not a red flag, but a direct consequence of its holding company model: a good part of White Mountains's accounting profit comes from marking its stakes (Ark, Kudu, and the investment portfolios of its insurance subsidiaries) to market value, not solely from collecting premiums minus claims paid. These gains are real and reflect genuine value creation, but they do not immediately translate into cash on hand, unlike the pure underwriting profit of an insurer like RLI.
One number illustrates the classic insurance mechanic well at White Mountains: its net cash collection cycle comes out at minus 558 days in my screen. In plain terms, the company collects premium money well before having to pay the corresponding claims, sometimes years in advance for certain long-tail reinsurance contracts. This money, called float, can be invested in the meantime. It is one of the most powerful mechanisms in the sector: in a way, the insurer borrows its policyholders' money for free (or nearly free) until claims come due.
The numbers side by side
| Criterion | RLI Corp (RLI) | White Mountains (WTM) |
|---|---|---|
| Quality score (my screen) | 9 / 10 | 9 / 10 |
| Business model | Direct underwriter (E&S) | Holding company, multiple stakes |
| Sales growth | +11.3%/year | +32.4%/year |
| Return on invested capital | 25.6% | 10.8% |
| Free cash flow margin | 28.9% | 16.4% |
| Net debt / free cash flow | 0.54x | 1.17x |
| Current P/FCF (valuation) | about 9.8x | about 8.7x |
| Reasonable buy price (my model) | $95.60 | $3,045.19 |
| Price mid-July 2026 | about $58 | about $2,140 |
What the table really shows
RLI clearly wins on capital efficiency: a 25.6% return on invested capital against 10.8% for White Mountains, and a free cash flow margin nearly twice as high. That makes sense: RLI is a pure specialty underwriter, focused on a business it has mastered for decades, while White Mountains manages a more diversified set of stakes, some of which are still ramping up (Ark, for instance, saw its combined ratio improve from 97% to 91% between the first quarter of 2025 and the first quarter of 2026, a good sign, but not yet at RLI's level).
On growth and valuation, the gap flips. White Mountains shows much faster sales growth (+32.4% per year against +11.3% for RLI), driven by Ark's ramp-up and gains in the value of its stakes. Both stocks trade below 10 times their annual free cash flow (P/FCF), a low level for companies scoring 9 out of 10, and my model puts a reasonable buy price well above the current share price in both cases. A gap that wide always deserves scrutiny rather than acceptance at face value: for White Mountains in particular, the NSM sale to Carlyle is not yet fully reflected in the financial statements my model uses, which may explain part of the apparent discount.
The real risk on each
For RLI, the risk is cyclical and sector-wide: a property and casualty insurance market that stays soft for longer could compress the combined ratio beyond 88.4%, cutting into the pure underwriting profit that drives the company's strength today. For White Mountains, the risk is more structural: the model's success depends on the quality of its leadership team's capital allocation decisions, what to buy, build, or sell, and at what price. A bad acquisition or a poorly negotiated sale would hit long-term value creation directly, in a way a pure insurer like RLI does not face in the same manner.
RLI reports second quarter results on July 22, 2026, White Mountains on August 10. For RLI, the question is whether the combined ratio stays under 90% despite the softer market. For White Mountains, the question is getting more detail on the timing and intended use of proceeds from the NSM sale.
How I am calling it
I never recommend a specific stock, but these two names suit different kinds of investors. RLI suits someone looking for a specialty underwriter that is profitable, A++ rated, with a history of discipline, even if that means accepting a less favorable sector cycle in the short term. White Mountains suits someone willing to trust a management team to allocate capital over time, with a concrete, near-term catalyst (the NSM sale) that could unlock a significant share of the company's value. Quality unites them, business model and risk profile separate them.
- RLI and White Mountains each score 9 out of 10 in my quality screen, but run different businesses: RLI underwrites its own risks (E&S), White Mountains owns stakes in several companies (Ark, Kudu, formerly NSM).
- RLI posts an 88.4% combined ratio and a 25.6% return on invested capital, well above White Mountains's 10.8%, but faces a softening property and casualty insurance market.
- White Mountains has signed the sale of NSM Insurance Group to Carlyle for $1.775 billion, more than a third of its current market cap, a major catalyst to watch.
- Both stocks trade below 10 times free cash flow (P/FCF), with my model's reasonable buy price well above the current share price in both cases.
- Two different profiles: RLI for pure underwriting discipline, White Mountains for a bet on the long-term capital allocation of a diversified compounder.
FAQ
What is the E&S (excess and surplus lines) market?
A roughly $300 billion segment of US insurance where insurers can freely set their own terms and pricing, unlike the standard admitted market regulated state by state. It covers risks too unusual or too volatile for generalist insurers.
What is the combined ratio in insurance?
Claims paid plus operating expenses, relative to premiums collected. Below 100%, the insurer makes money on underwriting itself, before even putting premium money to work. RLI posted 88.4% in the first quarter of 2026.
Why doesn't White Mountains's profit fully convert to cash?
A good part comes from marking its stakes (Ark, Kudu) to market value, not solely from collecting premiums minus claims. These gains are real but do not immediately translate into cash on hand.
What is float in insurance?
Premium money collected well before having to pay the corresponding claims, sometimes years in advance for certain contracts. This money can be invested in the meantime, one of the most powerful mechanisms in the insurance sector.
Should you buy RLI or White Mountains now?
Both score well on quality but have very different profiles: RLI for pure underwriting discipline, White Mountains for a bet on long-term capital allocation. This is not personalized investment advice, do your own research.
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About the author
Written by Lubin Danilo, founder of Lubin Investment. A self-taught individual investor, I find fundamental analysis fascinating, and it has delivered excellent results. For three years now, my performance has beaten the S&P 500. But analyzing every stock took too much time: sites with incomplete data, calculation methods and criteria never aligned with mine. And spotting the best stocks was just as time-consuming, even with my own well-defined checklist. So I put my software development background to work to build this software, base my investment strategy on its results, and share it with people who share the same passion as me. It judges a company's quality and its price separately, using criteria drawn from the financial literature (Warren Buffett, Michael Mauboussin, Aswath Damodaran).