Initial benefit claims rose by 78,000 to 439,000, partly due to a backlog of claims that could not be filed the week the hurricane hit and partly because some work has been suspended in the aftermath of the storm.
By close of trading Thursday, the Dow Jones industrial average lost 28.57 points or 0.23 percent to 12,542.38.
The Nasdaq was off 9.87 points or 0.35 percent to 2,836.94.
The Standard and Poor's 500 dropped 2.16 points or 0.16 percent to 1,353.33.
On the New York Stock Exchange, 999 stocks advanced and 2,086 declined on a volume of 3.8 billion shares traded.
The benchmark 10-year treasury was yielding 1.594 percent.
The euro rose to $1.2784 from Wednesday's $1.2735. Against the yen, the dollar rose to 81.21 from 80.25 yen.
In Tokyo, the Nikkei 225 index gained 1.9 percent, 164.99 points, to 8,829.72
In London, the FTSE 100 index lost 0.77 percent, 44.26, to 6,577.75.