The markets started the week on a positive note but by the end of the day had given back those gains. After the mornings rally, the indices pushed to new lows on the session, but were able to close off of them. The Dow 30 was off 14, the S&P 500 closed down 2, and the Nasdaq 100 closed lower by 7. Tomorrow the scheduled news if fairly light so traders will be looking for any catalyst to get to work.

Mattress Firm (MFRM  ) shot up a whopping 114% first thing this morning as the announcement came out that South African furniture retailer Steinhoff is buying the owner of Sleepy's for $2.4 billion, or $64 a share. That's a 110% premium based on Mattress Firm's closing price on Friday. The deal will give Steinhoff an entry into the US market.

Walmart (WMT  ) was pretty stable today (-0.57%) as news came out that the world's largest retailer said it would buy online retailer Jet.com for about $3 billion in cash. Analysts commented that the potential deal could help Walmart better compete with rival Amazon (AMZN  ) in the e-commerce space. The deal is expected to close this year.

Delta Air Lines (DAL  ) shares also remained stable (-0.61%) today despite news that the US airline carrier grounded all its flights worldwide. By the end of the day the airline started to resume some flights  following a system-wide computer failure that prevented passengers from checking in. "Our systems are down everywhere," Delta told customers via a Twitter post early this morning.

Monster Beverage (MNST  ) sold off 2.19% today after hitting new highs Friday following its earnings announcement. The stock gained 2.5% on Friday after the company reported a mixed quarter and authorized an additional $250 million in share repurchases, but today the selling persisted and erased all of Friday's gains.