Buying low to sell later when the stock's price is high is a time-honored investing strategy. With the benchmark S&P 500 index near its all-time high, though, now might seem like the wrong time to go looking for stocks that trade at bargain prices.

If a frothy market has kept you sidelined, I've got some good news. While most investors are focusing on the artificial intelligence (AI) revolution, a couple of terrific businesses are flying under the radar.

Shares of Pfizer (PFE 1.26%), and UnitedHealth Group (UNH 1.37%) have been beaten down to near 52-week lows. Here's why they look like terrific bargains right now.

1. Pfizer

Shares of Pfizer are down by about 57% from a peak they reached in late 2021. Sales of COVID-19 products that declined faster than expected, plus upcoming patent cliffs for its top-selling products, have kept the stock under pressure.

Pfizer's stock price has declined over the years, but not its dividend payout. In January, Pfizer raised its quarterly dividend payout for the 16th year in a row. At recent prices, the stock offers a huge 6.6% dividend yield.

In 2024, sales of a next-generation blood thinner called Eliquis grew 9% to $7.4 billion for Pfizer. That works out to 11.6% of total revenue. Unfortunately, generic versions of Eliquis are expected to launch in the U.S. market beginning in 2028, which could reduce this huge revenue stream down to a tiny trickle.

Patent cliffs are a problem for all big pharmaceutical companies. By reinvesting the profits that its aging blockbusters produce into an enormous development pipeline, Pfizer can offset the losses and continue growing its bottom line.

Pfizer has more than likely launched enough future blockbusters to offset upcoming Eliquis losses and continue pushing its big needle forward for at least another decade. In 2023, the Food and Drug Administration (FDA) approved nine new drugs from Pfizer's pipeline and last year was another big one. In 2024, the FDA granted more than a dozen approvals to Pfizer products.

Pfizer reported total revenue that rose by 7% last year. If we exclude declining sales of its COVID-19 products, total sales surged by 12% year over year. This year, management expects adjusted earnings to reach a range between $2.80 and $3.00 per share. That's a lot more than the company needs to meet a dividend obligation currently set at $1.72 annually. An upcoming patent cliff for Eliquis could limit growth, but not to a degree that makes it impossible to continue a steady pace of dividend payout raises.

2. UnitedHealth Group

Shares of UnitedHealth Group are down by about 25% from a peak they reached last November. Unexpectedly high healthcare utilization rates hammered profits and the stock price lower this year.

The stock has been falling because medical costs rose 9% in 2024 but total revenue climbed just 6% over the same period. As a result, net income declined by a striking 35% last year to $15.51 per share.

Hospitals have raised pries a little faster than UnitedHealth Group expected,but this enormous healthcare conglomerate has levers it can pull to keep its bottom line moving in the right direction. For starters, it can raise premiums that members and plan sponsors and their employees will most likely accept. After years of consolidation in the insurance industry, options are limited.

UnitedHealth Group doesn't just run America's largest private insurance operation, it's also the nation's largest employer of physicians. It's hard to imagine a better way for an insurer to retain more of the premiums it receives each month than by directly employing the physicians who order tests and procedures that drive up medical expenses.

In November of 2023, UnitedHealth's Optum Health division said it employed 90,000 American physicians, or roughly 10% of the total. At last November's investor day conference, management wasn't as vocal about how many physicians it employs but did mention it completed 16 million home health visits in 2024.

UnitedHealth Group stock price is down but the company has raised its dividend payout a whopping 94% over the past five years. At recent prices it offers a minuscule 0.4% yield but it's growing so fast that this stock could be a significant source of passive income by the time you're ready to retire. Adding some shares to a diverse portfolio now to hold over the long run looks like the right move.