The market has hit a rough patch this year, with the S&P 500 down by about 20% in 2022. However, even when challenges arise, certain stocks do well. One such stock is Kroger (NYSE: KR), which has gained about 6% during this span. While that may sound underwhelming, consider that performance trounced the overall market. Over the last three years, Kroger's stock has more than doubled, increasing by about 116%, almost four times the S&P 500's gain. While it's tempting to hop on the bandwagon, you shouldn't blindly invest in a stock merely based on past success. To determine whether or not Kroger's shares still present a good opportunity, it's time to delve deeper into the company's valuation and growth prospects. Image source: Getty Images. Valuation You can use various metrics to evaluate the price of a stock. While it's tempting to look at the share price, you should examine objective measures such as the price-to-earnings ratio (P/E). You can use this metric to compare how much investors are willing to pay for a company's earnings and compare that number historically and to other companies in the industry. Kroger's rapid stock price advance has meant that the equity now trades a P/E multiple of over 16 compared to under 10 times in 2019. It's also important to compare Kroger's P/E to similar companies. Albertsons Companies, a food and drug retailer, sells at an 18 multiple while Walmart has a 26 P/E. Hence, while the stock has become relatively more expensive, it sells at a discount to its peers. The key question becomes whether Kroger's stock warrants this higher relative valuation compared to a few years ago based on its growth prospects. Prospects Kroger has grown to become a large food, pharmaceutical, and gas retailer. The retailer sells basic, everyday items, so it's natural to expect a steady business no matter what's going on in the economy. This certainly helped the company during the pandemic. Consumers have a lot of options, though. But pushing its "leading with fresh and accelerating with digital" has been a powerful combination to remain competitive with the likes of Amazon and Walmart. For its fiscal first quarter (ended May 21), same-store sales (comps) excluding fuel rose by a solid 4.1%. Kroger's adjusted operating profit was $1.6 billion, 16.4% higher than a year ago. Management gave more optimistic guidance for this year. It expects comps to increase by 2.5% to 3.5%. Previously, the company called for a 2% to 3% comps increase. Like other retailers, Kroger has been dealing with higher supply chain costs. The company does have a vertically integrated supply chain that helps mitigates them. However, while the company increased this year's adjusted operating profitability expectations by $100 million to a range of $4.3 billion to $4.4 billion, the revised figure remains relatively flat from fiscal 2021's $4.3 billion. Kroger has a lot going for it. It's been generating consistent sales growth, and its profit has been increasing. However, with a higher stock valuation and a cautious operating income outlook for this year, I'd hold off on purchases right now. 10 stocks we like better than KrogerWhen our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Kroger wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of June 2, 2022 Lawrence Rothman, CFA has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source