A market crash can be a great time to add stocks to your portfolio. Even perfectly good stocks can plummet during a crash despite there being nothing fundamentally wrong with their businesses. And when their stock prices fall, it's an incredible opportunity for investors to buy them at lows that won't last for long.

Here are three stocks to put on your watch list. Keep some cash on the sidelines and be ready to pounce on them if and when the markets tumble again this year:

1. Starbucks

Starbucks (NASDAQ:SBUX) has a rock-solid business model that makes it too good to ignore if it goes on sale. The COVID-19 pandemic will negatively impact the company's near-term sales and profits, but it won't affect the coffee chain over the long term. What makes the stock an attractive buy is how flexible and adaptable the business is. As people continue social distancing, and whether they're working remotely or at the office, they can easily pick up their coffee order via drive-thru at a nearby Starbucks.

An investor in a busy office shows happiness over a transaction.

Image source: Getty Images.

In the company's second-quarter results, released on April 28, its sales dipped 5% from the prior-year period. However, Starbucks didn't start to close its stores due to the pandemic until March, which is why the company expects its third-quarter results to feel more of an impact from COVID-19. It also expects the fourth quarter to feel a moderate impact from the pandemic.

A possible market crash combined with some soft quarters ahead this year could send Starbucks back down near its 52-week low of around $50. That would be a bargain for the Seattle-based business, which hasn't traded below $50 in about two years. And even despite the poor result in Q2, Starbucks still recorded a net income of $328 million, which was more than 5% of its revenue. In previous quarters, Starbucks has typically netted a profit margin of at least 10%.

As a bonus, the stock also pays a quarterly dividend of $0.41, which yields 2.1% annually. That's slightly better than the average S&P 500 dividend yield of 2%.

2. Facebook

Facebook (NASDAQ:FB) is another business that looks to be recession-proof since users will flock to the service regardless of how well the economy is doing. The social media company's stock is even more resilient than Starbucks' since Facebook doesn't need a brick-and-mortar location to make sales. It's also a heck of a lot easier for its staff to work remotely than it is for employees of a company like Starbucks, which needs at least some in-store staff.

And Facebook expects that in the next five to 10 years half of its employees could be working remotely. That would decrease its need for office space and could help reduce overhead, making the company even more profitable.

In 2019, Facebook booked a profit margin of 26%. In each of the three years prior to that, that percentage was up over 30%. That means that even today, with the stock trading at more than 30 times earnings, it could still be a great long-term buy if it's able to simplify its operations in the coming years and bring its costs down.

On April 29, the California-based company released its first-quarter results of fiscal 2020. Its sales were still up 18% from the prior-year period, and the company's profits doubled, from $2.4 billion to $4.9 billion. But that growth may not be sustainable in the short term. According to projections by GroupM, a leading advertising company, spending on advertisements will likely decline in the U.S. from $238.8 billion in 2019 to $207.9 billion this year, for a drop of 13%. Facebook could be headed for some tougher quarters ahead if that proves to be true. 

And if the markets also crash, it could make the stock a dirt cheap buy, especially if it nears its 52-week low of $137.10.

3. Trulieve

Trulieve Cannabis (OTC:TCNN.F) is one of the safer pot stocks investors can buy today. Focused on the medical marijuana market in Florida, it's a lot less volatile than cannabis companies that depend on the strength of the recreational market. But that's not to say that Trulieve isn't expanding to other markets.

On June 4, the company announced that the Massachusetts Cannabis Control Commission (CCC) approved its Life Essence subsidiary for a provisional adult-use license, which will allow it to cultivate indoors and manufacture in Holyoke, Massachusetts. The CCC also approved a license for Trulieve to operate a retail shop in Northampton, Massachusetts. For now, the company's sales and growth come predominantly from the Florida market, where it has 48 of its 50 dispensaries.

When the Florida-based business released its first-quarter results on May 20, its operations were still strong, showing no adverse effects due to COVID-19. Sales of $96.1 million were up 21% from the previous quarter, and the company recorded net income of $14 million. Trulieve's posted a profit in each of its last four quarters. The company's stability makes it an attractive cannabis stock to keep on your watch list as a dip in price may not last long.

In March, when the markets were crashing, the stock fell below $6 a share. But even seeing the stock fall below $10 has been rare and that could be a great price to buy Trulieve at, should it be available. Trading at a price-to-earnings multiple of eight and a price-to-sales ratio of less than five, the stock's already reasonably priced and lower than where it's been at in the past. A further decline could make it an even better buy.

Which stock is the best buy today?

Here's how all three stocks have done this year compared with the S&P 500:

FB Chart

FB data by YCharts

While Facebook's performed the best thus far, it's not the stock that I'd buy today. Because I'm a bargain hunter and someone who loves dividends, Starbucks is the stock I'd add to my portfolio right now. It's a household name that you can hold in your portfolio for decades, and buying it on the dip could help secure some better returns later on. But if any one of these three stocks dips sharply in value during a market crash, investors shouldn't hesitate to scoop it up.