(Reuters) – The benchmark S&P 500 and the blue-chip Dow indexes were lower in afternoon trading on Friday as investors continued to grapple with concerns over a delay in corporate tax cuts, while the Nasdaq pared losses, helped by gains in Nvidia and media stocks.

Senate Republicans on Thursday unveiled a plan that would delay, by a year, lowering the corporate tax rate to 20 percent and provide small-business owners with a deduction rather than a special business rate.

The Senate Republicans’ version of the bill differs markedly on corporate, business and individual tax cuts from legislation detailed by their counterparts in the House of Representatives.

Expectations of lower taxes, one of President Donald Trump’s key promises, have helped powered the S&P more than 20 percent since the 2016 presidential election.

“When you get to the end of the earnings season, the focus shifts from the micro to the macro, in this case, the tax bill,” said Art Hogan, chief market strategist at Wunderlich Securities.

“The concerns over the differences between the Senate and House version of the tax bill is causing some consolidation in the market. It’s a pretty tight time frame for the passage of the bill and I think it will be an event for the first quarter.”

At 12:46 p.m. EDT (1646 GMT) the Dow Jones Industrial Average .DJI was down 46.94 points, or 0.2 percent, at 23,415, the S&P 500 .SPX was down 4.31 points, or 0.17 percent, at 2,580.31 and the Nasdaq Composite .IXIC was down 4.78 points, or 0.07 percent, at 6,745.27.

All three major indexes were on track to end lower for the week, with the S&P and the Dow set to end lower for the first time in nine weeks.

Six of the 11 major S&P sectors were lower on Friday, with the energy index’s .SPNY 1.23 percent fall leading the decliners as oil prices fell.

Nvidia (NVDA.O) jumped 5.8 percent, hitting a record high, after the chipmaker’s revenue forecast for the current quarter topped estimates.

A rise in media stocks also helped limit the slide.

Disney (DIS.N) rose 2.6 percent as the promise of a new “Star Wars” trilogy overshadowed its weak quarterly results.

Twenty-First Century Fox (FOXA.O), Time Warner Inc (TWX.N), Comcast (CMCSA.O) and News Corp (NWSA.O) were up between 1.0 percent and 7.5 percent, and were among the top boosts on the S&P and the Nasdaq.

Declining issues outnumbered advancers on the NYSE by 1,593 to 1,225. On the Nasdaq, 1,567 issues rose and 1,254 fell.