The is almost utterly unchanged over the past three or so months, ending Friday just 0.2 percent above its closing price on July 11. But while large-cap stocks have been treading water, a host of important indicators have been on the move.
In that same time period, oil has risen 12 percent, the U.S. dollar index has climbed about 2.5 percent and the yield offered by the 10-year U.S. Treasury note has risen by 25 percent. Notably, the bond and dollar moves have come as expectations for a 2016 Federal Reserve rate hike have increased.
To be sure, it's not as if equities have forgotten to respond to changes in the macro environment. As Eddy Elfenbein of the Crossing Wall Street blog pointed out, the technology sector ETF (XLK) has surged 7 percent since July 11, while the utilities ETF (XLU) has slid by more than 8 percent.
"Even though the market is fairly placid on the surface, we're seeing a changing tenor to the market," wherein "risk-friendlier areas have done quite while" while more bond-like high-dividend stocks have fallen, Elfenbein said Friday on CNBC's "Trading Nation."
"There are a lot of different moving parts that are moving different aspects of the market," echoed Stacey Gilbert, head of derivative strategy at Susquehanna. "The S&P is flat, but the underlying components to it certainly are not."
Gilbert pegs these changes on investors' embrace of risk and shunning of big dividend payers, which occurred as the market's (and with it, perhaps the Fed's) post-Brexit vote fear faded.
And for her, the contrast between a placid market surface and swiftly shifting undercurrents holds important implications for investment strategy.
"This is not a market to just buy the S&P 500 and expect it to be up on the year. In a lot of ways, those days are over. Now you have to be a lot more sophisticated in terms of picking your sectors, picking your stocks," Gilbert said Friday on "Trading Nation."
"This is where it becomes a lot more important to understand the stories" that are driving sector and single-stock moves, she added.