Markel Corp (MKL -1.00%) is an insurance holding company with a wide variety of products. Since its founding in 1930, the company has grown tremendously and continues to do so. What makes Markel different than the rest, and is it a good fit for your portfolio?

An insurance business like no other
What makes Markel different than most insurance companies is the sheer diversity and uniqueness of its product line.

The company's wholesale division provides insurance solutions for common purposes like commercial property and casualty as well as medical malpractice. However, Markel prides itself for its non-standard offerings like its DataBreach and professional liability insurance products, just to name a couple.

Markel's Specialty Commercial division offers even more unusual solutions, and specializes in quantifying risks that are tough to determine. For example, the company provides bicycle insurance policies, as well as solutions to insure camps and recreation programs, child care centers, health clubs, farms, investment advisors, and pest control providers.

A full list of their unique specialty commercial programs is available here, and is a very interesting and thought-provoking read. After all, how many other companies have more than 50 years of experience insuring show horses?

There is also an extensive list of personal products Markel provides. Want to specifically insure your karate classes? Want insurance in case your parents' anniversary party needs to be cancelled? You've found the right company.

Impressive growth
One of the reasons Markel has such an enormous array of products is its long history of acquisitions. Since the 1980's, Markel has acquired 15 separate companies, many of which were highly specialized, like a summer camp insurer and a trucking insurance specialist.

Most recently, Markel acquired Alterra Capital, a deal which nearly doubled its insurance portfolio, but even excluding that, the growth is impressive. Markel's portfolio of insurance premiums written has averaged an impressive 18% annual growth rate over the past two decades.

However, aside from the acquisitions, Markel has grown rapidly because it's very good at what it does – offering a unique product to consumers at a price that attracts business. It is also very good at judging risk, and has done a very good job of taking in more in premiums than it pays out.

Over the past decade, Markel's combined ratio (that is, the amount it pays out relative to the premiums it collects) has only been around 100% twice, and just barely, at 101% and 102%. During the past decade as a whole, Markel has averaged a combined ratio of just under 96%, meaning it is doing a very good job of approximating the risk their policies are taking on.

On top of this, Markel receives income from its investments while it holds the collected premiums in its accounts (this is actually how insurance companies make the bulk of their profits).

In fact, over the past 20 years, Markel's insurance portfolio per share has grown at an average annual rate of 13%.

It's relatively easy to quantify Markel's overall performance over the past few decades. The company doesn't pay a dividend, and instead feels its money is better spent reinvested into its business (sounds kind of like Warren Buffett). Over the past 20 years, shares have risen from $39 to about $647 as of this writing, for an average annual return of more than 15%. With returns like that, I'm inclined to agree with management on the no-dividend policy.

The bottom line
Markel is the kind of company any long-term investor should love, because it has a distinct competitive advantage in its extremely diverse and unique product portfolio.

Finally, one of the most compelling reasons to love Markel is its shareholder-friendly management. In the company's 2013 letter to shareholders, the company's board members wrote:

"This is your company. We as managers are stewards of your capital. You've entrusted us with the authority to run this business, and this annual report functions as our report card to you."

The management has delivered for its shareholders year after year.

If only every company's management thought like that...