Does the government shutdown have you feeling queasy about investing in stocks? It's understandable, but history says your portfolio's going to be just fine. The last government shutdown, in 2019, is hardly noticeable on a chart of the benchmark S&P 500 index's performance.

If you are concerned about the short-term performance of stocks, it's probably best to invest in businesses that pay dividends. It's a lot easier to remain stoic during market downturns when you know there's a quarterly dividend payment around the corner.

At recent prices, you can scoop up a share of Pfizer (PFE -0.48%), and a share of MPLX LP (MPLX -0.38%) for less than $100 combined. Here's why investors want to pick up both of these ultra-high-yield stocks now and hold on for the long run.

1. Pfizer

Pfizer became a household name during the COVID pandemic. That didn't prevent sales of vaccines and antiviral treatments that address COVID-19 from plunging over the past few years. In addition to sinking COVID sales, several blockbuster products are losing patent-protected market exclusivity soon.

From 2025 through 2030, Pfizer expects patent expirations to reduce annual sales by $17 billion to $18 billion. Fear that it won't be able to maintain its dividend payment has pushed the stock down by more than half from its previous peak.

The drugmaker has raised its payout every year since 2009. At recent prices, it offers a huge 6.4% yield.

While Pfizer's headed for significant losses due to patent expirations, it used the profits its COVID products generated to acquire new revenue streams. In 2024, regulators granted more than a dozen approvals to Pfizer drugs. It also has a big late-stage development pipeline that produced eight phase 3 clinical trial readouts last year.

In January, Pfizer said it expected acquired products to generate $20 billion in annual revenue by 2030. More recently, it announced the upcoming acquisition of Metsera and its experimental anti-obesity treatments. If either of Metsera's candidates continues to succeed in clinical studies, Pfizer's management team will have to significantly raise its 2030 revenue projection.

Over the next several years, Pfizer investors probably won't receive rapid payout raises. With a robust development pipeline, though, there's a good chance that dividends will keep moving in the right direction.

2. MPLX LP

It's hard to find a more reliable business than pushing a fuel supply through pipelines. Folks are going to heat their homes in good economic times and bad ones, too. Reliable cash flows are a big reason that MPLX has been able to raise its dividend payout by 103.5% over the past 10 years.

MPLX LP is a master limited partnership (MLP), which means its shareholders, or partners, are responsible for paying income taxes on its distributions. Your accountant most likely won't recommend putting MLP shares, or units, in a tax-advantaged retirement account. With a 7.7% yield at recent prices, though, it's a worthwhile investment even if your distributions are taxed as regular income.

In 2012, MPLX, spun off from Marathon Petroleum, a leading oil refiner. Marathon Petroleum still owns a stake in MPLX and is a reliable source of revenue.

Volumes are still on the rise, but earnings growth has slowed due to rising operating expenses. Despite the challenge, MPLX's dividend is on a stable footing. Free cash flow that reached $4.82 per share over the past 12 months is more than sufficient to meet its dividend obligation, which is currently set at $3.826 per share. Adding some shares to a diversified portfolio now looks like a great way to build a stream of passive income that can fuel your retirement plans.