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Here are five things you must know for Friday, Aug. 18:

1. -- A terror attack in Spain kept gains in U.S. stock futures to a minimum on Friday, Aug. 18. 

The S&P 500 and Dow Jones Industrial Average were little changed, while the Nasdaq made small moves higher. 

A stock selloff on Thursday, Aug. 17, sent benchmark indexes lower. A disappointing quarterly performance from Cisco Systems Inc. (CSCO)  triggered losses in the tech sector and led to a triple-digit decline on the Dow Jones Industrial Average. 

All Dow components ended in the red on Thursday, while the benchmark index suffered its worst daily performance since May. 

2. -- A terrorist attack in Spain set European markets on edge on Friday. 

Police shot dead five suspected terrorists, hours after a van slammed into a crowd in Barcelona on Thursday afternoon. Police killed the five would-be attackers in Cambrils, south of Barcelona, who had been planning a separate related attack, according to Reuters. The planned attack involved explosive belts, though those have now been determined to be fake. 

On Thursday, a van ran into a crowd along the tourist-heavy Las Ramblas avenue. That attack killed 13 people and injuring more than 100 others. ISIS claimed credit for the incident. 

3. -- Gap Inc. (GPS) moved higher in premarket trading Friday morning thanks to quarterly earnings more than double a year earlier. 

The casual clothing retailer earned 68 cents a share over its quarter ended July 29, far better than a 31 cents a share a year earlier and higher than estimates of 52 cents. 

Sales declined by 1.4% to $3.8 billion, but also exceeded estimates. Analysts anticipated $3.77 billion. 

The company's lower-priced Old Navy line, which has bolstered the stock in recent quarters, reported same-store sales increasing 5%. The Gap and Banana Republic brands' same-store sales fell 1% and 5%, respectively. It was an improvement on the same quarter a year earlier when Old Navy same-store sales came in flat, Gap fell 3%, and Banana Republic declined by 9%. 

All performed better than in 2016, when Old Navy same-store sales were flat, Gap's fell 3% and Banana Republic's fell 9%.

4. -- Estee Lauder Companies Inc. (EL) and Deere & Co. (DE) will report earnings before the bell Friday.

Retail earnings have dominated the tailend of the reporting season. Disappointing earnings from J.C. Penney (JCP) , Advanced Auto Parts Inc. (AAP) , and Coach Inc. (COH) have countered positive reports from Walmart Stores Inc. (WMT) , Target Corp. (TGT) , TJX Companies Inc. (TJX) , and Home Depot Inc. (HD) .

Around 92% of S&P 500 companies have reported earnings so far this season. Of those, 73.7% have exceeded earnings estimates, above the historical average of 64%, according to Thomson Reuters data. More than 68% have topped revenue consensus, also above an average of 59%.

Consumer discretionary and staples stocks have seen the slowest earnings growth, up 3.6% and 4.6%, respectively.

5. -- It's a quieter day on the economic calendar on Friday with just a preliminary reading on consumer sentiment for August out at 10 a.m. ET. The weekly read on U.S. drilling activity from Baker Hughes will be released as normal at 1 p.m. ET.

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