(CNN Money) -- The stock market's six-day winning streak is over.
Walmart had its worst day in three decades, bond yields inched up again, and the Dow closed down more than 250 points.
Disappointing online sales drove Walmart stock down more than 10%, its worst day since January 1988. Online sales were up 23% from a year ago, but that was much slower than the previous nine months — a sign that Walmart is finding it more difficult than expected to compete with Amazon.
The yield on the 10-year U.S. Treasury note rose to 2.91%, the highest in four years. Rising yields coupled with interest rate hikes from the Fed to stave off inflation could make bonds more attractive to investors, and thus drag down stocks.
The Treasury Department is auctioning off $258 billion of debt this week to help pay for tax cuts and increased spending.