S&P zeroes in on 2,300 as the postelection rally chugs along

Do you like round numbers in the stock market? Then be on the lookout for the next one.

The S&P 500 on Wednesday was within half a percent of hitting 2,300 for the first time, following the Dow Jones industrial average on the milestone train. While 2,300 may not look as sexy as the Dow's 20,000, the S&P's round number may be more significant.

"The Dow is interesting because it's been around for so long, but the one that matters is the S&P," JJ Kinahan, chief market strategist at TD Ameritrade, told CNBC in December. "Almost every single professional investor that I know measures his or her performance against the S&P; very few measure it against the Dow."

The S&P is made up of 500 of the nation's largest publicly traded companies, encompassing 11 wide-ranging sectors, including energy, information technology and real estate. The Dow, on the other hand, has only 30 stocks and doesn't cover such a wide variety of industries.

The S&P has come within striking distance of 2,300 on the back of a massive post-U.S. election rally. Since Nov. 8, the index has spiked around 7 percent, with financials and materials leading the way, as optimism about the possibility of tax cuts, fiscal spending and deregulation of certain sectors has flooded the market.

S&P 500 since US electionSource: FactSet

Now, when the S&P will reach 2,300 is anybody's guess, TD Ameritrade's Kinahan said. "If I knew where we go from there, I wouldn't be talking to you. I'd be on a yacht."