Earnings Season Off to Slow Start, Clouding the Outlook for Stocks

Early reports put focus on threat of an economic slowdown, the pressure of rising costs on profits

Investors hoping a strong start to earnings season would jolt the stock market from its slump haven’t gotten much satisfaction.

Early reports from U.S. companies have refocused attention on some of the biggest challenges facing businesses, from the threat of an economic slowdown to the pressure that rising costs are putting on corporate profits. JPMorgan Chase JPM -1.03%▼ & Co., Delta Air Lines Inc. DAL 3.49%▲ and industrial supplier Fastenal Co. FAST -0.31%▼ are among those last week that warned they are facing strains or see clouds ahead.