A Big Mac, a Coke and a data breach — 5 things to know today by Ben Geier @FortuneMagazine October 21, 2014, 8:10 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons Good morning, friends and Fortune readers.U.S. stocks look set to move higher at Tuesday’s opening bell, as investors digest a raft of earnings from Dow components McDonald’s, Coca-Cola, Verizon and others. Later in the day we’ll hear from Marissa Mayer’s Yahoo. Plus, China posted its slowest economic growth since the financial crisis, and the country’s market was down at the end of trading. Here’s what else you need to know.1. Big Mac and a Coke, anyone?Both McDonald’s MCD and Coca-Cola KO report quarterly earnings today. Both companies have been hurt by changing consumer demand lately, as people are drinking less soda and leaning towards “fast casual” restaurants rather than eating fast food.Will either company be able to right their ship? Not Coke, which said soda volumes were flat in the third quarter. Earnings and revenue both declined, and the soda maker disclosed a new cost-cutting plan. Separately, McDonald’s said its third-quarter earnings drop was worse than expected and laid out a fix for its deepening sales decline.2. Who’s moving?Existing home sales data for September are due out later this morning. They were down last month after four months of steady growth. People selling their homes tend to go out and buy new houses, so a rebound would be a good sign for the economy.3. Another data breachData breaches at large retailers seem to come every day now, and Staples SPLS is the latest retailer to announce a breach, according to CNBC. The office supplier hasn’t announced specifics yet, but said credit card data may have been taken.4. Sad news from RussiaChristophe de Margerie, the CEO of French oil company Total, died when his plane crashed near Moscow. The larger-than-life de Margerie, 63, was on his way back from a meeting between foreign investors and the Russian government when his Dassault executive jet hit a snowplow, killing him and the three crew members on board. 5. Does Marissa Mayer have a miracle?According to reports, no. Yahoo YHOO will report its earnings this afternoon, and it is expected to miss analysts’ expectations as the one-time tech giant continues to disappoint. Could the rumored purchase of video ad company Brightroll change things?