The second trading session of September could look much like the first, with the fluctuating around all-time highs.
Investors on Tuesday returned after a long holiday weekend to better-than-expected reports on manufacturing and construction spending only to pay them little heed, with the S&P 500 rising to another intraday record early on before turning negative.
Read MoreU.S. stocks finish mixed; S&P 500 clings to 2,000
"We've had a pretty good chain of reports, which could justify why the S&P 500 is at an all-time high. But there is both a psychological and technical resistance at 2,000; we've really consolidated around that level for the last five sessions," said Randy Frederick, managing director of trading and derivatives at Charles Schwab.
Like Tuesday, investors on Wednesday could bypass economic reports that include factory orders for July, the Federal Reserve's Beige Book and motor vehicle sales for August, while waiting to hear from the European Central Bank and its president, Mario Draghi, on Thursday, and then the nonfarm payrolls report for August on Friday.
"Wednesday is just as lackluster in terms of its catalysts as today (Tuesday) has been. A good deal of this week's catalysts are in front of us," said Art Hogan, chief market strategist at Wunderlich Securities.
In Jackson Hole, Wyoming, last month, Draghi said the ECB would use "all the available instruments needed to ensure price stability" in the European Union, where the threat of deflation looms, with the inflation rate in the 18-nation euro zone declining to a five-year low of 0.3 percent in August.
And, worsening economic conditions in Europe could increase chances of additional stimulus when the ECB meets Thursday.
"What we are really trying to figure out is what can the ECB do here? They will most likely lower rates; they will either speak to the framework for asset purchases, or they may actually announce the start of it. The upside surprise would be the announcement of an asset-purchase program. No conversation at all and keeping rates unchanged, that would be the negative news," Hogan said.
"I'm leaning towards listless trading in anticipation that the ECB goes the way of the Fed and begins, continues or extends their own quantitative easing program. The markets are going to be looking for some concrete steps. I don't see a ton of trading ahead of that, unless there is continued geopolitical news," said Paul Nolte, senior vice president, portfolio manager at Kingsview Asset Management, in trying to anticipate Wednesday's trade.
"We had a really good week last week and a very good August, so maybe there is some profit-taking. It's not happening on a ton of volume. Activity will pick up, but not until Thursday and Friday," Nolte added.
—By CNBC's Kate Gibson