Entering trading on Monday, the S&P 500 has declined around 6% since the start of the year. And that's after recovering recently -- it was down much more than that in early April when global tariffs were first announced. But make no mistake, the risk isn't gone, and while a full-blown crash has taken a pause lately, that doesn't mean more of a sell-off isn't coming.

The good news, however, is that if you're a long-term investor, a crash in the markets can open up some great buying opportunities. Three stocks that are down over 10% this year and trading at low earnings multiples are Pfizer (PFE 3.38%), PayPal (PYPL 2.19%), and Builders FirstSource (BLDR -1.09%). Here's why they may be worth loading up on right now.

Pfizer

Investors haven't been all that bullish on Pfizer this year -- it's down 13% thus far in 2025. But it's hard to blame the market for the lack of excitement as the business is struggling to grow these days, as Pfizer expects its top line this year to be nearly unchanged from the previous year, and at worst, it could decline.

For long-term investors, this presents a great chance to load up on the healthcare stock. It trades at a forward price-to-earnings (P/E) multiple of less than 8 (based on analyst expectations), and the company has been gearing up for more growth ahead. CEO Albert Bourla has acknowledged that the company will face adversity because of generics, which could result in it losing as much as $18 billion in revenue from its top line by the end of the decade. But at the same time, through in-house development and acquisitions, it plans to add $25 billion.

It has acquired multiple businesses in recent years, including oncology company Seagen, in an effort to bolster its long-term prospects. Management expects Seagen could contribute up to $10 billion in revenue by the end of the decade (up from over $3 billion last year). Pfizer is also optimistic about its mRNA pipeline, projecting that business to bring in between $10 billion and $15 billion by 2030.

Last year, it also obtained approval for a gene therapy treatment, Beqvez, to treat adults with moderate to severe hemophilia B (a rare bleeding disorder). The gene therapy market is in its early stages but it has the potential to be a huge opportunity for pharma giants like Pfizer. Overall, the company has a wealth of assets in its pipeline with currently more than 100 drug candidates in clinical trials.

It'll require some patience, but investing in Pfizer can be a good move for the long term, especially when you consider that it also offers a mouthwatering dividend yield of over 7% right now.

PayPal

Fintech stock PayPal is another deeply discounted option to load up on today. According to analysts, it's trading at only 13 times its future earnings. The stock is down more than 20% this year, and concerns about the global economy aren't helping; a slowdown would mean less spending and travel, which would hurt PayPal's near-term growth prospects.

However, PayPal is still in an excellent position to benefit in the long run. The economy has and likely always will recover from a downturn. And provided that you're willing to hold for the long term, PayPal can be a top stock to hold. Not only is it cheap, but it's still a top payment option for consumers. Despite the growing number of options out there, PayPal still accounts for nearly half (45%) of the global payments market.

The company is also trying to be a bigger player in the crypto market, using that to its advantage with the launch of a stablecoin, PayPal USD. And the company recently introduced an attractive 3.7% yield on the coin to entice investors. The caveat -- the rewards can be used within PayPal's ecosystem, which could drive more transactions and revenue growth. By leveraging the excitement in the crypto world, PayPal may unlock more opportunities. And it's also a sign of the company's forward-thinking management; this isn't just a stale payment processor to invest in.

Last year, the company's payment volume rose by 10%, and while the near term may be a concern for PayPal, in the long run, this can make for an excellent investment to buy and hold.

Builders FirstSource

Another cheap stock to buy today is Builders FirstSource, which trades at a forward P/E of less than 13. It plays a crucial role in homebuilding, providing workers with building materials, products, and services. It stands to benefit significantly from the housing market's long-term growth.

While sentiment is down these days due to concerns about the economy and the company's slowing growth in recent years (its sales declined by 4% in 2024 to $16.4 billion), the business is likely to recover in the future. Between a growing population and a high cost of living, it's crucial for new homes to be built -- and Builders FirstSource is in a prime position to benefit from that.

The company has come a long way from where it was five years ago; in 2020, Builders generated $8.6 billion in sales. But through a red-hot housing market and the pursuit of acquisitions, which remain a key part of its growth strategy, the business has become much bigger today.

Builders deployed $352 million across 13 acquisitions last year, in an effort to expand its reach. It's now in 43 states, with around 590 locations. And with an increasingly diverse mix of products and services, it's better equipped to meet the needs of homebuilders. This year, the company projects that the acquisitions it completed with the last 12 months will generate between 4% and 4.5% net sales growth. With nearly $1.5 billion in free cash flow generated last year, Builders is still in good shape to continue pursuing acquisitions to further enhance its growth prospects.

Though the stock is down 15% this year because of recent performance and a poor short-term outlook, it’s still a great long-term investment.