Investing too much in one's home market is an investment risk that often goes unnoticed. That is particularly true for U.S. investors, given the size of Wall Street relative to other global markets. One way to address this issue is to add a few specific foreign stocks to your portfolio. Luckily, you can do that on a U.S. exchange by buying stocks like The Bank of Nova Scotia (BNS -1.04%), Shell (SHEL 0.49%), and Unilever (UL 0.19%). Here's a quick look at each of these solid passive income plays.

North and south

Bank of Nova Scotia, often shortened to Scotiabank, is one of Canada's largest banks. The Canadian banking market is highly regulated and protected since the government seems averse to allowing big mergers, and smaller players have difficulty competing with the entrenched leaders. In addition, Canadian banks tend to be somewhat conservatively managed overall. That makes The Bank of Nova Scotia an interesting option for even risk-averse types looking for income. The bank's current dividend yield is a healthy 5.1%.

So, you get Canadian exposure here, but that's not all. Scotiabank also has sizable exposure to South America, a global wealth management business, and banking operations in other foreign countries. All in, foreign businesses make up 66% of earnings. So, this more than 100-year-old bank provides you with a solid foundation (Canadian banking) that supports more growth-oriented operations, notably in emerging South American markets. That's not a bad option for long-term investors.

Back to dividend growth

Globally integrated energy giant Shell cut its dividend in 2020, which would normally suggest investors should tread cautiously. However, management did so in support of a major business shift. Essentially, it decided that to ensure the company's long-term future, Shell needed to more aggressively shift toward clean energy options like solar and wind while paring back on carbon fuels like oil. It has been working toward that goal, which offers investors an "all of the above" investment on the energy front. Meanwhile, while present in the U.S. market, Shell has operations spanning the world.

That said, another key goal was to start growing the dividend again. Since 2020, Shell has increased the dividend four times. Management is basically doing exactly what it said it would, and that, coupled with the dividend increases, should give income investors a lot of confidence in the future of this over 100-year-old energy company.

The current dividend yield is 3.5%. An interesting bonus here, given the high rate of inflation, is that oil stocks like Shell are actually benefiting as higher commodity prices flow through to their top and bottom lines. That could help soften the blow of the rising prices you are facing in your own life.

Out of favor, for now

The last name up is consumer staples giant Unilever. The stock yields a historically high 4.3%. The yield is high because Unilever's performance lags behind many of its closest peers. That's the bad news.

The good news is the company owns some of the world's best-known brands, including Dove and Ben & Jerry's, among many others. It also generates almost 60% of its sales from emerging markets, where long-term growth will likely be more robust than in developed markets. There's some U.S. exposure in the company's developed markets business, but it is modest and not enough to bring the company's foreign stock status into question.

And notably, Unilever recently added dissident shareholder Nelson Peltz to its board. Peltz was involved in the turnaround of peer Procter & Gamble. Although there's no way to predict whether the same magic will take shape at Unilever, some important similarities (company size, brand strength, and a need for management simplification) suggest the future could be brighter than investors seem to believe today.

Broaden your horizons

If you are looking to create a solid stream of passive income, you'll want to do a deep dive on The Bank of Nova Scotia, Shell, and Unilever. One of these foreign stocks will likely pique your interest enough to find its way into your portfolio. In fact, you might end up buying more than one. If you do, though, you should keep in mind that U.S. investors generally have to pay foreign taxes on foreign dividends and that dividends paid in a foreign currency will lead to slight quarterly variations when translated into U.S. dollars.