By Keith Speights

May isn't historically the best month for stocks. However, that doesn't mean it isn't a good time to buy stocks. If you're a long-term investor, buying when the past favors a less robust performance can work to your advantage.

The question, though, is: Which stocks should you buy? Different investors will have different opinions. Here are my picks for the top three stocks to buy in May.

Image source: Getty Images.

1. TransMedics Group

Warren Buffett's mentor, Benjamin Graham, wrote a classic book titled The Intelligent Investor years ago. In his book, Graham described an allegorical character, Mr. Market, who sometimes made rash decisions that created buying opportunities. I think Mr. Market is at work with TransMedics Group (NASDAQ: TMDX), seeing a sharp decline this year.

TransMedics Group developed the Organ Care System (OCS), a technology that keeps donor hearts, lungs, and livers functioning until they can be transplanted into recipients' bodies. The company also built its National OCS Program (NOP) to handle the complex logistics required for organ transplants, including assembling a fleet of aircraft to transport donor organs.

Mr. Market is focused primarily on TransMedics' first-quarter 2026 earnings miss right now. The company reported adjusted earnings per share of $0.30, well below the consensus Wall Street estimate of $0.61. Although TransMedics' revenue jumped 21% year over year in Q1, its operating expenses grew even more. Management attributed the higher expenses to increased research and development costs and to investments in growing the business.

The important thing to me is that the company's long-term prospects remain bright. TransMedics has begun operations in Italy, the first step in a planned expansion across Europe. It's developing a next-generation version of OCS that could accelerate growth. Most exciting, though, the company is working on an OCS for kidney transplants. Roughly 40% more kidneys are transplanted each year than hearts, lungs, and livers combined. I think this medical device stock is a bargain after its steep sell-off.

2. Rhythm Pharmaceuticals

Rhythm Pharmaceuticals (RYTM) is another healthcare stock that has fallen year to date. However, the drugmaker's shares have begun to rebound. I expect the momentum will continue for three key reasons.

First, Rhythm recently picked up two regulatory approvals for Imcivree in treating acquired hypothalamic obesity (HO). The U.S. Food and Drug Administration (FDA) approved the drug on March 19, 2026. The European Commission granted marketing authorization for Imcivree in the acquired HO indication on May 1.

Second, Japanese regulators are reviewing Rhythm's filing for Imcivree in treating acquired HO, with a decision expected in the second half of 2026. Acquired HO affects more than 25,000 patients in the U.S., Europe, and Japan. This number is more than 3x greater than the total patient population for Imcivree's previously approved indications.

Third, Rhythm plans to announce six-month results from its ongoing Phase 2 clinical trial evaluating Imcivree for the treatment of Prader-Willi Syndrome (PWS) within the next couple of months. PWS is a rare disease characterized by insatiable hunger. It presents a huge market for the company, affecting an estimated 400,000 patients worldwide (with around 20,000 of them in the U.S.)

3. Enbridge

TransMedics Group and Rhythm Pharmaceuticals are admittedly aggressive picks. Is there a good choice in May for more risk-averse investors? Yep. Enbridge (ENB) looks like an ideal candidate, in my view.

Enbridge's pipelines transport 30% of the crude oil produced in North America and around one-fifth of the natural gas consumed in the U.S. I'd say that's sufficient to make the company a critical component of our national energy infrastructure. Such stocks often provide stability to volatile portfolios.

This article was originally published by The Motley Fool