In just the past two years, the S&P 500 has amassed some incredible gains, rising by around 60% during that stretch. It's an incredible performance when you consider its long-run average is a return of approximately 10% per year.

During this period, quite a few stocks have generated supersized returns, thanks to solid underlying businesses that created, or intend to create, immense value in the products and services they offer. Three stocks that have been 10-baggers in just the past two years are Summit Therapeutics (NASDAQ: SMMT), Carvana (NYSE: CVNA), and Nvidia (NASDAQ: NVDA). But is it too late to buy these stocks, or can they still climb higher?

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Summit Therapeutics: Up 1,600%

Pharmaceutical company Summit Therapeutics has been a raging-hot buy of late after investors learned that its cancer drug, ivonescimab, performed better than Keytruda in a recent lung cancer trial. Keytruda has been a top-selling drug for years, generating billions in revenue for Merck -- a company whose market cap of $270 billion is nearly 17 times more valuable than Summit, even with the smaller pharma stock's recent surge.

Investors are clearly pricing in not just the approval for ivonescimab, but for it to be a huge moneymaker for Summit in the future. With no source of recurring revenue right now, that's a bit of a risk for investors to take with the healthcare stock today. While the trial was encouraging, it was conducted in China, and it may not be diverse and convincing enough for regulators in the U.S. to grant approval.

Given its enormous gains of late, investors may want to take a wait-and-see approach with Summit's stock today. While it still may possess a lot of upside, investors shouldn't overlook the high risk it contains, either.

Carvana: Up 1,330%

Shares of online used-car dealer Carvana have been skyrocketing this year as investors grow bullish on the auto market while interest rates come down. Another reason investors are excited for Carvana is that the company's financials have been showing improvement. It has reported profits in recent quarters, making investors less worried about the company's viability.

Demand for used cars could rise amid a downturn if cash-strapped consumers look for more affordable vehicle options. But with modest gross margins of less than 20%, there's not a big buffer there for the business to manage any headwinds and rising costs. Carvana will need to run a tight ship to ensure it is able to stay out of the red. Last year, it incurred an operating loss of $72 million.