What happened Shares of hotel giant Marriott International (NASDAQ: MAR) fell as much as 6.9% on Friday after a massive data breach was revealed. Shares were still down 5.5% at 12:10 p.m. EST and look to be holding at about that level. So what Marriott said that since 2014, there has been unauthorized access to names, mailing addresses, phone numbers, email, passport numbers, and other information from hotels once owned by Starwood, which was acquired by Marriott in 2016. The breach could affect as many as 500 million people, although the exact number is still being determined. Image source: Getty Images. The data breach was only flagged in September, so the investigation is in its early stages and Marriott doesn't have an estimate of financial impact. But if previous incidents like this are any indication, it could result in customers booking at other hotels until the smoke blows over. Now what Unfortunately, breaches like this are something we see all too often at companies with consumer data, and it appears that Starwood has had a problem with security for many years. It's also likely there will be financial costs associated with lawsuits or remedies the company offers to customers. But long term, companies haven't had data breaches devastate their business, and this will likely blow over when enough time has passed. 10 stocks we like better than Marriott InternationalWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has quadrupled the market.* David and Tom just revealed what they believe are the 10 best stocks for investors to buy right now... and Marriott International wasn't one of them! That's right -- they think these 10 stocks are even better buys. Click here to learn about these picks! *Stock Advisor returns as of November 14, 2018Travis Hoium has no position in any of the stocks mentioned. The Motley Fool recommends Marriott International. The Motley Fool has a disclosure policy.