What happened E-commerce stocks got hit hard on Monday as the market reacted to a game-changing development in the race for a COVID-19 vaccine. As of 2:30 p.m. EST, shares of Amazon.com (NASDAQ: AMZN), Square (NYSE: SQ), PayPal (NASDAQ: PYPL), and Shopify (NYSE: SHOP) were down 3.3%, 6.1%, 7.1%, and 10.5%, respectively. So what Online retail and digital payments have been some of the best-performing stocks of 2020, as investors have sought out shelter from the COVID storm. E-commerce businesses -- many of which have seen their sales soar during the coronavirus pandemic -- have provided a welcome refuge. Prior to today, shares of Amazon, PayPal, Shopify, and Square had surged 79%, 87%, 163%, and 217%, respectively, since the end of 2019. Investors sold off shares of e-commerce companies on Monday. Image source: Getty Images. However, after Pfizer and BioNTech's blockbuster announcement on Monday that clinical trial results suggest their coronavirus vaccine candidate, BNT162b, could be more than 90% effective at preventing COVID-19, many investors apparently decided to take profits in e-commerce stocks. Now what After incredible advances this year, it's understandable that some people would want to lock in some gains. But it's important to note that the migration of retail sales to online channels -- and with it, the shift from cash to digital transactions -- will not come to a halt after the COVID-19 crisis subsides. These are powerful long-term trends that should continue to propel the growth of Amazon, Square, PayPal, and Shopify for many years to come. Investors, therefore, would likely be best served by holding on to the stocks of these e-commerce leaders. Find out why Amazon is one of the 10 best stocks to buy now Motley Fool co-founders Tom and David Gardner have spent more than a decade beating the market. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* Tom and David just revealed their ten top stock picks for investors to buy right now. Amazon is on the list -- but there are nine others you may be overlooking. Click here to get access to the full list! *Stock Advisor returns as of October 20, 2020 John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Joe Tenebruso has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Amazon, PayPal Holdings, Shopify, and Square and recommends the following options: short January 2022 $1940 calls on Amazon, long January 2022 $1920 calls on Amazon, and long January 2022 $75 calls on PayPal Holdings. The Motley Fool has a disclosure policy.Source