Editor's pick: Originally published June 22.

Updated from June 22 with Brexit vote details.

Uh oh. 

Investors are shell-shocked Friday by British voters' surprising decision to exit the European Union and David Cameron's ensuing announcement that he would step down as prime minister. In Europe, the German DAX plunged 8%, while London's FTSE 100 nosedived about 8% and the broad Stoxx Europe 600 index shed 8%. France's CAC 40 slid 9%. Dow Jones Industrial Average futures fell as much as 700 points. 

The U.K.'s surprising move may lead to some ugly times ahead for its economy. 

The International Monetary Fund has said the impact of Britain's departure from the European Union would be "negative and substantial." The IMF predicted that a "Brexit" could reduce economic growth in the U.K. by up to 5.6% over the next three years in its worst-case scenario. Such a dire outlook would be fueled by a projected sharp decline in the pound and massive disruptions in trade as the nation will have to renegotiate deals with countries across the continent, possibly on worse terms.

More broadly, now that the U.K. has decided to leave the E.U. it may cause other large countries to reassess their membership. And that could really make things dicey for U.S. multinationals.

"If Germany leaves the eurozone, you would expect the new Deutsche Mark to be much stronger than the euro and if others leave, they might have much weaker currencies," cautioned former Bank of England Governor Mervyn King in a March 22 interview with TheStreet.

TheStreet takes a brief look at three consumer focused U.S. multinationals whose out-sized exposure to the U.K. could take a bite out of performance as a result of the Brexit.

The U.K. has a ton of Starbucks locations. They may be empty due to the Brexit.

1. Starbucks

The United Kingdom is Starbucks' (SBUX - Get Report) largest European market at about 870 stores, followed by Germany (158) and Russia (105). In total, Starbucks operates 2,448 company-operated and licensed locations in its European, Middle East and Africa segment (EMEA) compared to more than 12,000 in the U.S. and 1,963 in China.

Starbucks is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio.

Brexit could hit Starbucks in several ways. 

First is via the company's retail stores. Europe has become more lucrative for Starbucks following a decision several years back to close underperforming locations (mostly in the U.K.) and focus on a licensing model, instead of directly operating stores in traditionally high-cost European regions. For the fiscal year ended Sept. 27, Starbucks sales in its EMEA segment fell 6% year over year to $1.2 billion, but profits surged 41.1% to $168.2 million. More recently, sales and operating profit for Starbucks' EMEA segment fell 4% and 5%, respectively, for the second quarter ended March 27 due to sluggish travel trends in Europe in the wake of several high-profile terror incidents.
The business represented roughly 6.3% of Starbucks' sales in the last fiscal year, and 4.7% of its operating profit.
If the U.K. goes into a state of chaos following the Brexit, the number of people visiting Starbucks retail stores could decline. 
Starbucks is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio . Want to be alerted before Cramer buys or sells SBUX? Learn more now.
Second, a post-Brexit state of chaos in the U.K. could reduce the return potential for a couple new initiatives from Starbucks. Starbucks begins the rollout this summer of its pods for the Nespresso home brewing machine in its stores, online and where groceries are sold in the U.K. and France. According to Starbucks, Nespresso's largest market is Europe, and in some countries single-serve coffee consumption represents over 40% of all coffee consumed. The company estimates about 50% of its best Starbucks customers own a Nespresso machine at home.
The company will also debut its first-ever store in the de facto coffee capital of the world -- Italy -- in early 2017.

The last thing Walmart needed was a Brexit. Its U.K. operations have not done well of late. 
2. Walmart 
The world's largest retailer Walmart ( WMT - Get Report)  can't be happy about the Brexit. Walmart's already struggling U.K. division Asda -- which numbers about 400 stores -- may now see even weaker sales amid a consumer spending pullback.  
Asda's first quarter same-store sales plunged 5.7% in the first quarter. Store traffic fell 5%, while the average amount spent by customers declined 0.7%. The showing was by far the worst among Walmart's international divisions, and represented the seventh straight quarterly sales decline for the U.K. outfit.
Walmart pinned the blame on "significant structural shifts" in the U.K. market, primarily the rise of hard discount chains such as Aldi and Lidl. In reality, Walmart's competitors in the U.K., such as Tesco and Sainsbury, have simply gotten better at offering deal-seeking Brits good discounts on apparel and food.
"We are very disappointed with the performance of Asda," David Cheesewright, president and CEO and Walmart's international operations, conceded to reporters at a gathering ahead of the retailer's annual shareholder meeting earlier this month. To try and correct the performance, said Cheesewright, Walmart will be investing some $250 million in lower product prices. It also recently appointed a new chief for Asda, who is unlikely keen on having to evaluate the brand while trying to compete in a challenging post Brexit U.K.

Who will want to buy an expensive Tiffany ring amidst economic unrest?  
3. Tiffany
High-end jeweler Tiffany ( TIF - Get Report) does a fair amount of business in Europe via large flagship stores, in particular the U.K. Sales in Europe represented 12% of Tiffany's worldwide sales last year, while sales in the U.K. alone accounted for about 40% of its European net sales.
Tiffany operates about 41 stores in Europe, which is its third largest international market behind Asia-Pacific (81 stores) and Japan (56 stores). By region, the U.K. boasts 11 stores, the biggest by far among major European markets such as Germany, Italy, France, Spain, Russia, and Switzerland.
The Brexit could lead to reduced shopping levels at the company's important U.K. stores as consumers fret about their financial outlook. In turn, that may accentuate an already weak sales trend for Tiffany on the continent.
Tiffany's first-quarter sales in Europe fell 9% from the prior year to $97 million, while comparable store sales plunged 15%. Excluding the strength of the U.S. dollar, net sales and same-store sales fell 7% and 14%, respectively during the quarter. The company blamed lower tourism spending, mostly in France in the wake of several terror related incidents, for the sales declines.