Many large U.S. companies have seen their stocks swell since the presidential election.

The top 10 performing stocks in the S&P 500 index saw returns of 18% or more since Election Day, according to data provided by S&P Global Market Intelligence, which analyzed returns based on closing prices from Nov. 5 to Nov. 20.

Two companies — Axon Enterprise (AXON), which provides law-enforcement technology, and Tesla (TSLA), the electric-vehicle maker led by Elon Musk, an advisor to President-elect Donald Trump — saw their stocks gain more than 35%, according to S&P Global Market Intelligence.

By contrast, the S&P 500 gained about 2% over the same period.

Investors should be cautious about buying individual stocks based on short-term boosts, said Jeremy Goldberg, a certified financial planner, portfolio manager and research analyst at Professional Advisory Services, Inc., which ranked No. 37 on CNBC’s annual Financial Advisor 100 list.

“It’s usually a bad idea,” Goldberg said. “Momentum is a powerful force in the market, but relying solely on short-term price moves as an investment strategy is risky.”

Investors should understand what’s driving the movement and whether the factors pushing up a stock price are sustainable, Goldberg said.

Companies in the streaming ecosystem — like Warner Bros. Discovery (WBD), which owns the Max streaming service, and Disney+ owner The Walt Disney Co. (DIS) — may be benefactors of looser rules around consolidation, they said.

For example, Palantir Technologies (PLTR), cited “unprecedented” demand for its AI platform in the third quarter, helping deliver “exceptionally strong” earnings, Treasurer and CFO David Glazer told investors Nov. 4.

Likewise, Axon beat analysts’ estimates in its Nov. 7 earnings results, with officials touting its “AI era plan” and raising earnings guidance, Goldberg said.

Axon and Palantir stocks were up 38% and 22%, respectively, from Nov. 5 to Nov. 20, according to S&P Global Market Intelligence.

Some companies benefited from a combination of policy and earnings, experts said.

Take Vistra Corp. (VST), an energy provider, for example. The company’s stock jumped 27% after Election Day.

Vistra is in talks with large data centers — or “hyperscalers” — in Texas, Pennsylvania and Ohio to build or upgrade gas and nuclear plants, Stacey Doré, Vistra’s chief strategy and sustainability officer, said on the company’s Q3 earnings call Nov. 7.

Tech companies are building more and more such data centers to fuel the AI revolution — and need to source increasing amounts of energy to run them.

Musk, Tesla’s CEO, was one of Trump’s top campaign backers. Trump tapped him to co-lead a new Department of Government Efficiency. Shares of the electric-vehicle maker soared 14% the day after the election and almost 30% by week’s end.

But Tesla stock has additional tailwinds, experts said.

For one, Trump wants to end a $7,500 federal tax credit for EVs. Scrapping that policy is expected to hurt Tesla’s EV rivals.

Tesla has also been developing technology for driverless vehicles. In Tesla’s recent earnings call, Musk said he’d use his influence in Trump’s administration to establish a “federal approval process for autonomous vehicles.”

With the Biden administration’s new student loan repayment plan is tied up in legal battles, millions of borrowers have had their monthly payments put on hold.

The break from the bills is likely a relief to the many federal student loan borrowers enrolled in the Saving on a Valuable Education plan, known as SAVE. But it may also be causing them anxiety over the fact that they won’t get credit on their timeline to debt forgiveness.

For example, those also enrolled in the Public Service Loan Forgiveness program, who are entitled to loan cancellation after 10 years, have seen their journey toward that relief halted during the forbearance.

“Borrowers are frustrated about the delay toward forgiveness,” said higher education expert Mark Kantrowitz. “They feel like they’ve been waiting for Godot.”

Here’s what borrowers enrolled in SAVE should know about the delay to debt cancellation.

In October, the U.S. Department of Education said that roughly 8 million federal student loan borrowers will remain in an interest-free forbearance while the courts decide the fate of the SAVE plan.

A federal court issued an injunction earlier this year preventing the Education Department from implementing parts of the SAVE plan, which the Biden administration had described as the most affordable repayment plan in history. Under SAVE’s terms, many people expected to see their monthly bills cut in half. 

The forbearance is supposed to help borrowers who were counting on those lower monthly bills. But unlike the Covid-era pause on federal student loan payments, this forbearance does not bring borrowers closer to debt forgiveness under an income-driven repayment plan or Public Service Loan Forgiveness.

Adding to borrowers’ annoyance is that “those enrolled in the SAVE Plan were not given the choice of forbearance,” said Elaine Rubin, director of corporate communications at Edvisors, which helps students navigate college costs and borrowing. If borrowers want to stay in SAVE, they can’t opt out of this pause.

Borrowers enrolled in PSLF are especially concerned, Kantrowitz said. That program requires borrowers to work in public service while they’re repaying their student loans.

“They have been working in a qualifying job, but aren’t making progress toward forgiveness,” he said. “Some borrowers are working a job they hate, but are sticking with it in the expectation of qualifying for forgiveness. Others are close to retirement and don’t want to have to work past their normal retirement age just to get the forgiveness.”

You may be able switch into another income-driven repayment plan that is still available. Under that new plan, you may have to start making payments again. Yet if you earn under around $20,000 as a single person, your monthly payment could still be $0, and therefore you might not lose anything by switching, Kantrowitz said.

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Changing plans might be especially appealing to those who are very close to crossing the finish line to debt forgiveness and just want to see their balance wiped away, experts said. (You’ll likely be placed in a processing forbearance for a period while your loan servicer makes that switch. During that time, you will get credit toward forgiveness.)

The Education Department is also offering those who’ve been working in public service for 10 years the chance to “buy back” certain months in their payment history. This allows borrowers to make payments to cover previous months for which they didn’t get credit. But to be eligible for the option, the purchased months need to bring you to the 120 payments required for loan forgiveness.

“The buyback option might be eliminated under the Trump administration,” Kantrowitz said. “So, if you want to use it, you should use it now.”

Many employees have a health savings account, which offers tax incentives to save for medical expenses. However, most are still missing out on long-term HSA benefits, experts say.

Two-thirds of companies offer investment options for HSA contributions, up 60% from one year ago, according to a survey released in November by the Plan Sponsor Council of America, which polled more than 500 employers in the summer of 2024. 

But only 18% of participants invest their HSA balance, down slightly from the previous year, the survey found.

That could be a “huge mistake” because HSAs are “the only triple-tax-free account in America,” said certified financial planner Ted Jenkin, founder and CEO of oXYGen Financial in Atlanta.

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Health savings accounts are popular among advisors, who encourage clients to invest the funds long term rather than spending the funds on yearly medical expenses. But you need an eligible high-deductible health plan to make contributions.

Some 66% of employees picked an HSA-qualifying health plan when given the choice, according to the Plan Sponsor Council of America survey.

However, the best health insurance plan depends on your family’s expected medical expenses for the upcoming year, experts say. Typically, high-deductible plans have lower premiums but more upfront expenses.

“It’s one way to deal with the inflationary cost of health care,” said Jenkin, who is also a member of CNBC’s Financial Advisor Council. “If you invest it wisely, it can look like a health 401(k).” 

A 65-year-old retiring today can expect to spend an average of $165,000 in health and medical expenses through retirement, up nearly 5% from 2023, according to a Fidelity report released in August.

That estimate doesn’t include the cost of long-term care, which can be significantly higher, depending on needs.