U.S. stocks skidded Thursday after Senate Republicans surprised Wall Street by proposing a delay in cutting corporate taxes. Industrial and technology companies fell the most, but stocks pared their losses in afternoon trading.

On Thursday:

The Standard & Poor’s 500 index slumped 9.76 points, or 0.4 percent, to 2,584.62.

The Dow Jones industrial average sank 101.42 points, or 0.4 percent, to 23,461.94.

The Nasdaq composite retreated 39.07 points, or 0.6 percent, to 6,750.05.

The Russell 2000 index of smaller-company stocks declined 6.71 points, or 0.5 percent, to 1,475.02.

For the week:

The S&P 500 is down 3.22 points, or 0.1 percent.

The Dow is down 77.25 points, or 0.3 percent.

The Nasdaq is down 14.38 points, or 0.2 percent.

The Russell 2000 is down 19.89 points, or 1.3 percent.

For the year:

The S&P 500 is up 345.79 points, or 15.5 percent.

The Dow is up 3,699.34 points, or 18.7 percent.

The Nasdaq is up 1,366.94 points, or 25.4 percent.

The Russell is up 117.89 points, or 8.7 percent.