U.S. stocks struggled to hold onto slight gains on Friday as a terrorist attack in France overnight cast a shadow of worry over global markets.

The S&P 500 was up 0.11%, the Dow Jones Industrial Average added 0.17%, and the Nasdaq was flat.

At least 84 people were killed in Nice, France overnight after a heavy truck tore through crowds celebrating Bastille Day. The attacker was shot dead by officers after engaging in gunfire. French President Francois Hollande called the attack terrorism and has called for three days of mourning beginning on Saturday.

In light of the attack, Republican presidential candidate Donald Trump delayed an event on Friday in which he was expected to announce his vice presidential pick.

European markets were lower. The CAC 40 in France fell 0.54%, the DAX in Germany slid 0.13%, and the FTSE 100 in London slipped 0.04%.

Travel stocks were declining on the expectation terrorism fears would impede demand. U.S. airlines including Delta (DAL) - Get Report , United Continental (UAL) - Get Report , and JetBlue (JBLU) - Get Report were each lower in early Friday trading. Cruise operators Carnival (CCL) - Get Report and Royal Caribbean (RCL) - Get Report were also lower.

U.S. retail sales increased in June as consumers showed more confidence in spending than saving. Sales rose 0.6% last month, driven by big gains at home-improvement and garden retailers. Sales at stores such as Home Depot (HD) - Get Report enjoyed their largest monthly gain in six years. Economists had expected sales to inch 0.1% higher. The consumer has grown more willing to part with cash on signs the U.S. economy is on the mend.

The Consumer Price Index in June rose 0.2%, in line with estimates. Increases in the cost of gas, rent and medical care countered declines in food prices. Excluding food and energy, core consumer prices rose 0.2% in June.

Consumer sentiment in July weakened, according to the latest reading from the University of Michigan. Sentiment fell 89.5 in July, likely a fallout from market turmoil in the wake of the United Kingdom's vote to leave the European Union. 

Industrial output in June rose at its fastest pace in nearly a year as the headwinds of a stronger U.S. dollar and weaker international demand began to fade. Gains in auto and utility output drove the headline number higher. Industrial production grew 0.6% in June, above an estimated 0.5% increase. May's decline of 0.4% was revised to show a 0.3% decrease. 

Wells Fargo (WFC) - Get Report reported an in-line second-quarter with adjusted earnings of $1.01 a share. Revenue climbed nearly 4% to $22.16 billion, as analysts expected. A prolonged period of low interest rates kept profit under pressure.

Citigroup (C) - Get Report moved higher after topping estimates in its second quarter. The bank earned $1.24 a share, 14 cents higher than expected. Revenue sank 10% to $17.55 billion, though came in $80 million above forecasts.

"Broad-based strength across all core business segments demonstrates the resilience of Citi's operations against the backdrop of a challenging and volatile global economic environment, while expense management is improving the company's operational leverage," said Jim Cramer and Jack Mohr, portfolio managers of theAction Alerts PLUS Charitable Trust Portfolio. AAP holds WFC and C.Learn more now.

U.S. Bancorp (UBS) - Get Report rose more than 1% after exceeding expectations in its recent quarter. The bank reported net income of 83 cents a share, 3 cents higher than a year earlier. Revenue climbed just more than 8% to $5.45 billion.

Manufacturing conditions in the New York region softened in July, according to the Empire State Manufacturing Survey. The general business conditions index declined to 0.6 in July from 6 in June, potentially weakened by the impact of the Brexit vote late June.

The S&P 500 closed out Thursday's session with its fourth record close in a row as hopes for global monetary stimulus kept hopes high on Wall Street. The benchmark index gained 0.52%, securing a record close of 2,164. The Dow scored a record close for its third day in a row, climbing 0.73% to 18,506.

AdvancePierre Foods (APFH) rose 11% to hover above $23 in its debut day of trading. The packaged foods company had priced its initial public offering at $21. 

Herbalife (HLF) - Get Report surged to its highest level in two-and-a-half-years after the Federal Trade Commission agreed to settle for $200 million. The FTC determined the health company is not a pyramid scheme.

Xerox (XRX) - Get Report reportedly has rejected a bid to merge its document-printing business with R.R. Donnelley & Sons (RRD) - Get Report . The Xerox board reviewed the proposal and decided its plan to separate into two companies by year's end held less risk.