When you survey the thousands of companies in the stock market, looking for an investment that might build your wealth over the long term, give some consideration to Warren Buffett's company, Berkshire Hathaway (BRK.A -2.74%) (BRK.B -2.81%).

It has an amazing track record, as Buffett, in concert with his late business partner Charlie Munger, increased the value of the company by 5,500,000% (nearly 20% annually) over 60 years. In contrast, the S&P 500 index of 500 of America's biggest companies gained about 39,000% (10.4% annually, on average) -- which is still a solid performance.

Warren Buffett.

Image source: The Motley Fool.

Why invest in Berkshire now? Well, it's reasonably valued. Its recent forward-looking price-to-earnings (P/E) ratio of 23.6 is a bit above its five-year average of 21.0, and its price-to-sales ratio, recently 2.5, is a bit above the five-year average of 2.2. This suggests that Berkshire isn't a screaming buy right now, but the price is within reason for long-term investors.

If you invest in Berkshire, you'll get a lot for your money. You'll become a part-owner of scores of businesses owned by Berkshire, such as GEICO, Benjamin Moore, See's Candies, and the entire BNSF railroad. You'll have a stake in Berkshire's stock portfolio, too, with major positions in companies such as Apple, American Express, Coca-Cola, and Bank of America.

The company is simply built to last, with much of its value in resilient industries such as energy, insurance, and transportation. It's worth noting that Buffett, at age 95, will be stepping down from the CEO post at the end of the year, though he'll remain involved. He has long planned for this transition and has named longtime Berkshire executive Greg Abel to take the reins. He has two capable investing lieutenants as well.

Berkshire's future may be different from its past, but it still looks promising. If at some point Abel sees Berkshire with much more cash than it can use effectively, a dividend might even appear.