Last week, the Index came close to closing above a key level. Actually, it didn't come close.

It came very, very, very close.

The S&P 500 rose 2.7 percent over the course of the week, and hit its highest level in nearly two months after a strong February jobs report. In Friday's session, it also crossed above the key level of 2,000, which has developed importance for both psychological and historical reasons.

Read More Dow closes at 2-month high after jobs

It didn't close above that level, however. Instead the S&P 500 closed at 1,999.99 — or more specifically, at 1,999.98722585876.

Never before has the S&P 500's closing price been that close to a number divisible by 100. Before Friday, the S&P had never seen a "99.99" close, Howard Silverblatt, senior index analyst at S&P Dow Jones Indices, told CNBC.

Silverblatt adds that there have been two closes right at a 100.00 value, but not in a while. The two dates in question are October 25th, 1979 and July 28th, 1978 — with the index closing at 100.00 each time.

Fun facts aside, the market's reticence around this particularly level may be telling.

Frank Cappelleri has been keeping a close eye on 2,000 lately. A market technician and sales trader at Nomura-owned agency broker Instinet, Cappelleri says that "it's been a line on people's radar screens."

"Everybody knows it's there," he said. "It's psychologically important not only because it's a round number," he said, but also because it serves as the bottom of the market's trading range from mid-October to early January.

Based on Friday's close, it's likely a spot at which you see a short-term pause," Cappelleri predicted.

Chicago-based trader Brian Stutland is of a similar mind.

"There's no question that when you have a big number like that, everybody watches it," he said. "I wonder if people are anticipating that it gets to that point, and then takes a breather."

For Stutland, who has recently found himself taking a more bullish stance on stocks, 2,000 looks to be "a number we consolidate at before moving higher."

"Sometimes the market likes to find a nice, big, whole number to sit on and take a break before picking a direction — and right now, it looks like that number is 2,000," he said Friday.

Of course, the market is not managing to sit on it, exactly. For right now, the S&P is still 0.006 percent shy.

—By CNBC's Alex Rosenberg.

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