U.S. Stocks Open Lower

The U.S. stock market opened slightly lower on Wednesday as investors awaited a string of speeches by Federal Reserve officials. Traders are also tracking the U.K.'s invocation of Article 50, which officially starts that country's withdrawal from the European Union. The S&P 500 opened 4 points, or 0.2%, lower at 2,354. Shares of Vertex Pharmaceutical Inc. jumped 20% as one of its drugs had completed late-stage trials. The Nasdaq Composite fell 2 points, or less than 0.1%, at 5,873. The Dow Jones Industrial Average was down 43 points, or 0.2% at 20,656 at the open.