Wall Street closed lower on Thursday, pressured by declining shares of Walmart (WMT) all while investors look ahead to Federal Reserve Chair Jerome Powell’s upcoming speech at Jackson Hole on Friday.

Wall Street's main indexes fell on Thursday as investors awaited monetary policy clues from the Federal Reserve's annual economic symposium, while big-box retailer Walmart's quarterly results dampened sentiment.

U.S. stock futures showed little movement Thursday as investors prepared for the start of the Federal Reserve’s Jackson Hole symposium and awaited new labor market data. Attention also turned to Walmart,

Beyranevand says it’s possible that a particular food product could become contaminated if it was raised or farmed somewhere with elevated levels of Cs-137. Either way, she believes the breaded frozen shrimp recall is “definitely a cause for concern” for the food industry-at-large.

Walmart is recalling certain frozen shrimp products sold under its Great Value brand after the U.S. Food and Drug Administration (FDA) warned that the seafood may be at risk for radioactive contamination.

Shares of Walmart are trading more than 5% lower following the world’s largest retailer’s quarterly earnings release. The results, announced this morning, triggered a selloff that pushed the stock below key technical support levels.