Too many people focus more on the split part of a stock split than they do on the stock itself. The splitting of shares may or may not provide a catalyst. Even if it does, though, the bump will only be a temporary one. However, a great underlying stock can deliver solid gains for years and even decades. 

There are quite a few stocks with share prices so high that they're good candidates for stock splits. Here are two potential stock-split stocks you can buy and hold forever.

Markel Group: Diversification and growth in one stock

Markel Group (MKL -1.00%) has never conducted a stock split in its history. But with its share price currently well above $1,300, it wouldn't be surprising if the company's management hasn't at least considered the possibility.

Perhaps the most remarkable thing about Markel is the diversification it offers. Buying the stock is almost like investing in an exchange-traded fund (ETF).

Markel's core business is specialty insurance, but it also operates in the reinsurance market. Premiums from these insurance businesses generated roughly 65% of Markel's total operating revenue last year.

But the company also owns a controlling interest in nearly 20 companies through its Markel Ventures unit. These businesses span multiple industries, including construction, energy, food, healthcare, and real estate.

In addition, Markel invests heavily in other publicly traded companies. It currently owns over 100 stocks. There are some ETFs (with fewer holdings than in Markel's portfolio).

I think Markel's portfolio features many stocks with tremendous long-term growth potential. The company's underlying insurance businesses should also generate steady cash flow. Few stocks provide the combination of diversification and growth that Markel does.

MercadoLibre: Profit from two unstoppable trends

Try to think of 10 unstoppable trends -- areas that will almost surely continue to enjoy increasing adoption for years to come. I suspect for many, e-commerce and fintech would make the list. MercadoLibre (MELI 3.09%) is a potential stock-split stock that offers investors a way to profit from both of these unstoppable trends.

Like Markel, MercadoLibre has never split its stock. Its share price of over $1,200 makes the stock a great candidate for a split, though.

MercadoLibre reigns as the king of the Latin American e-commerce market. It operates in 18 countries, including Argentina, Brazil, Colombia, and Mexico. The company's e-commerce platform ranks as the market leader in every major country where it's available, based on unique visitors and page views.

Even with its impressive growth in recent years, MercadoLibre should still have plenty of room to run in e-commerce. In Latin America, the e-commerce penetration rate remains well below that in the U.S. Morgan Stanley projects that the region's e-commerce market could increase by more than 50% by 2025. 

MercadoLibre has used its e-commerce success as a springboard into the fintech market. The company's fintech business is growing much faster than its e-commerce business. MercadoLibre now has roughly 44 million quarterly unique active fintech users, a number that should continue to increase significantly in the future.

Expanding its fintech customer base isn't MercadoLibre's only goal, though. It also hopes to deepen its relationships with its users. Over time, MercadoLibre intends to become the principal financial services platform for its customers throughout Latin America.

Split or no split

Neither Markel nor MercadoLibre has publicly indicated an interest in conducting a stock split, to my knowledge. Perhaps neither company will ever split its stock. 

Even if they don't, though, they're both great picks for long-term investors. And always remember ... the stock is more important than the split.