Say hello to earnings season! Fourth-quarter reports have begun to stream in and the better-than-expected results within the Dow Jones Industrial Average were largely responsible for the highest close on the S&P 500 (^GSPC -0.73%) since Dec. 2007.

The surprising boost came from insurance giant Travelers (TRV -0.40%), which crushed Wall Street's expectations by reporting a profit of $0.72 vs. expectations of just $0.14. Revenue of $5.39 billion also topped analyst expectations by $50 million. The company's management team remained visibly cautious on its growth prospects given both a record-low interest rate environment and a history of damaging storms in recent years hitting the U.S., but it nonetheless represents a jumping-off point for other insurance companies yet to report.

On the day, the S&P 500 advanced 6.58 points (0.44%) to close at 1,492.56.

Travelers' shareholders had a very good day, with their stock advancing 2%, but the biggest winners came from the hard-disk drive sector and the oil and gas sector.

Both Seagate Technology (STX) and Western Digital (WDC -0.22%) led the charge higher within the S&P 500, rising 7% and 6%, respectively. It's a little difficult to pinpoint a reason for the move other than the fact that Western Digital is scheduled to report its second-quarter results tomorrow and investors are anticipating a much-better-than-expected quarter. This could indeed be the case since Seagate issued preliminary quarterly guidance two weeks ago that was way ahead of Wall Street's forecast.

On the one hand, these very PC-dependent storage plays have seen PC sales shrink and spending on infrastructure remain tepid at best leading up to the fiscal cliff resolution. On the other hand, a pick-up in infrastructure spending by the nation's biggest telecoms within the past few weeks could be the impetus needed to spur big data center spending, where Seagate and Western Digital will be called on to provide vast storage needs. Overall, I am keeping a positive outlook on the storage sector.

The third-best gainer within the index today was Chesapeake Energy (CHKA.Q), up 5%. The oil and natural gas giant advanced as the coldest air mass of the year descended on the heart of America, boosting the prospect that heating fuels will be in high demand over the next few days. Last winter, warmer-than-expected weather crushed natural gas prices and hurt the bottom line of numerous drillers, including Chesapeake. With a renewed focus on liquid fuels (oil and natural gas liquids), as well as a return to weather that's at least semi-normal, Chesapeake shares may actually turn out to be quite the bargain in 2013 -- as long as CEO Aubrey McClendon doesn't screw it up, that is!