Trading Nation

On top: The 5 stocks that have doubled this year

The stocks that have doubled this year
Nasdaq 100 nears all-time high
How to trade Apple ahead of earnings

It's been a volatile but ultimately mild year for stocks, with the roughly flat for 2015. But a few choice names are bucking the trend. In fact, five stocks in the broad S&P 1500 index have managed to more than double this year.

The best-performing name among in that mega-index (which is comprised of all of the stocks in the large-cap S&P 500, in the mid-cap S&P 400, and in the small-cap S&P 600) is LendingTree. The company that connects lenders to consumers has seen its shares rise an incredibly 150 percent this year.

The stock's latest jump came on Monday, when (TREE) grew 23 percent after reporting earnings that beat estimates, and impressed investors with their 2016 guidance.

The company has done "two big things this year: They have created a great customer acquisition platform for mortgage lenders and expanded their business with the large retail banks. And the emergence of new personal loan lending clubs have helped them gather new customers," said Kerry Rice, an analyst with Needham, who is one of the few to cover the company.

LendingTree may also have been helped by low interest rates, which have likely spurred home purchases and refinancing decisions, particularly amid concerns that rates will soon rise.

"Due to the nature of the mortgage lending industry, interest rate increases may negatively impact future revenue from the company's lender marketplace," the company warned in its earnings report.

Still, Rice remains bullish on the $122 stock, with a "buy" rating and a price target of $140 (substantially above the $56 target the same analyst had back in February).

Read More Nasdaq 100 nears tech bubble record—time to worry?

Meanwhile, the only doubler that resides in the S&P 500 is Netflix. Despite a sharp slide after earnings earlier this month, the online media company has still managed to rise 110 percent in 2015.

Rounding out the list are medical implant company Abiomed, "small molecule therapeutics" company Cambrex, and a telecom construction company with the dystopian-sounding name of "Dycom Industries."