The sideshow in Washington continues as the government slowdown begins another week, and debt ceiling negotiations look like a non-starter. Both the Dow Jones Industrial Average (DJINDICES:^DJI) and the S&P 500 are fairly depressed this morning, and it seems a sure bet that a looming default on the U.S. debt is making markets nervous.

Happy faces
Some Dow companies are up today, notably AT&T (NYSE:T) and Verizon (NYSE:VZ) -- and they may have tech giant Apple to thank for it. The latter's spiking 5S and 5C iPhone sales have lifted its fortunes recently, and iPhone vendors AT&T and Verizon are sharing the spotlight, too, as both communications companies see increased sales for the popular gadgets.

Deals offered by big-box retailers Best Buy and Wal-Mart, which offer the iPhone 5C for half off the retail price -- and come with two-year contracts with AT&T, Sprint, or Verizon -- certainly can't be hurting, either.

Long faces
Many Dow components are listless today, with financials looking particularly wan. With no specific news about credit card issuers Visa (NYSE:V) and American Express (NYSE:AXP) on tap today, those companies could be suffering from a general fearfulness surrounding the debt ceiling crisis, and the effect that a lack of congressional action will have on the country's credit. Both credit card companies have experienced stellar share price growth over the past year, with Visa soaring by almost 34%, and American Express increasing by 25%.

JPMorgan Chase is also a laggard, reflecting some of the general malaise affecting markets so far today. Possibly causing some additional pain was a midmorning report on mortgage rates, in which analysts noted the huge jump in long-term interest rates since May. This has effectively cut the pool of refinance candidates in half, not good news for banks.

Fool contributor Amanda Alix has no position in any stocks mentioned. The Motley Fool recommends American Express, Apple, and Visa. The Motley Fool owns shares of Apple, JPMorgan Chase, and Visa. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.