Investors sold off stocks across the board Thursday as the partial government shutdown dragged into a third day and the US inched toward a deadline on raising the nation’s borrowing limit. Investors also got some disappointing economic news: The Institute of Supply Management reported that sales and new orders fell and hiring weakened at service companies. Stocks pared some of their losses in the afternoon after The New York Times said House Speaker John Boehner told his party he won’t let the nation default. Despite the recent slump, stocks are still close to the record levels they reached last month. The S&P 500 is up 17 percent this year.