Here are five things you must know for Tuesday, Aug. 7:   

1. -- Stocks Rise as Earnings Drive Gains

U.S. stock futures were higher on Tuesday, Aug. 7, and global stocks rebounded as earnings continued to impress and the S&P 500 edged closer to the all-time high it reached in January.

Contracts tied to the Dow Jones Industrial Average  rose 82 points, and futures for the S&P 500 rose 5.50 points, pushing the index closer to its all-time high of 2,872.87 achieved on Jan. 26. Nasdaq futures on Tuesday were up 17.75 points. The Nasdaq rose Monday, Aug. 6, for a fifth straight session, the tech-heavy index's longest winning streak since May.

With around 71% of the S&P 500 having issued quarterly reports so far this season, earnings are expected to grow by 23.5% over the three months ended in June, a figure that would top the gains recorded over the first quarter and mark the best reporting period in eight years. More than 79% of companies have beaten consensus earnings estimates, according to Thomson Reuters data, well ahead of the 72% average for the past four quarters.

The economic calendar in the U.S. on Tuesday includes the Job Openings and Labor Turnover Survey for June at 10 a.m. ET.

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2. -- Disney, Papa John's and Snap Are Highlights of Tuesday's Earnings Calendar

Office Depot Inc. (ODP)  said adjusted earnings in the second quarter were 5 cents a share, 2 cents ahead of estimates. Sales of $2.63 billion also beat forecasts. Shares rose 1.2% in premarket trading on Tuesday.

Dean Foods Co. (DF)  fell 10.1% in premarket trading after the company cut its profit outlook for the full year. The company's earnings and sales in the second quarter beat analysts' forecasts.

Earnings reports are also expected Tuesday from Walt Disney Co. (DIS) , Avis Budget Group Inc. (CAR) , Fossil Group Inc. (FOSL) , Discovery Inc. (DISCA) , Emerson Electric Co. (EMR) , Hostess Brands Inc. (TWNK) , LendingClub Corp. (LC) , Papa John's International Inc. (PZZA) , Wendy's Co. (WEN)  and Snap Inc. (SNAP) .

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3. -- Justice Department Challenges Judge's OK of AT&T-Time Warner Merger

The Justice Department argued Monday that U.S. District Judge Richard Leon, who approved AT&T Inc.'s (T) merger with Time Warner Inc. , was wrong in concluding the combination won't harm consumers.

Leon misunderstood the complexities of the booming pay-TV market and the nature of AT&T's competitors, the DOJ's antitrust regulators asserted in a filing that challenged the judge's decision.

But AT&T General Counsel David McAtee said there's nothing in the government's new filing that should lead to Leon's ruling being overturned. "Appeals aren't 'do-overs'," McAtee said in a statement, the Associated Press reported.

AT&T closed the purchase of Time Warner for $85.4 billion -- $108.7 billion including assumed debt -- in June.

4. -- Carl Icahn Goes Public With His Opposition to Cigna-Express Scripts Deal

Billionaire activist investor Carl Icahn went public with his campaign to sink Cigna Corp.'s (CI) $54 billion plan to buy Express Scripts Holding Co. (ESRX)  .

Icahn sent an open letter Tuesday urging fellow Cigna shareholders to vote against the deal, which he calls a "$60 billion folly" carrying a "ridiculous" price tag. The Wall Street Journal first reported that Icahn planned to issue the letter on Tuesday.

"Cigna is dramatically overpaying for a highly challenged Express Scripts that is facing existential risks on several fronts," Icahn wrote in his letter.

The Journal had previously reported that Icahn bought a sizable Cigna stake, and would vote against the health insurer's proposed purchase of  pharmacy-benefit manager Express Scripts.

5. -- Weight Watchers Falls Despite Earnings Beat 

Weight Watchers International Inc. (WTW)  fell 3.8% in premarket trading on Tuesday despite a 28% year-over-year increase in subscribers at the weight-loss company during the second quarter and a 20% jump in revenue to $410 million.

The 4.5 million subscribers in the second quarter was, however, a decline from 4.6 million subscribers in the first quarter.

Earnings at Weight Watchers rose to $1.01 a share from 67 cents a year earlier. Analysts expected profit of 88 cents a share in the latest second quarter.

Weight Watchers also raised its full-year earnings outlook to a range of $3.10 to $3.25 a share, up from previous guidance of $3 to $3.20 a share. 

"Not only do we have the capability to transform the quality of our customers' lives, but now we also have the permission to be a bigger part of their lives," Weight Watchers CEO Mindy Grossman told TheStreet's Tony Owusu in an interview. "We want to help people more substantially, so we have evolved our brand to become a 365-day-a-year campaign."

Shares of Weight Watchers have risen more than 120% over the past 12 months.