Traders work on the floor of the New York Stock Exchange (NYSE).

Three weeks ago the yield on the 10-year Treasury was above 2.60 percent with the Federal Reserve about to raise rates and various economic surveys indicating confidence surging under President Donald Trump.

But something curious has happened.

The 10-year yield has dropped, trading near 2.30 percent this week as "hard" economic data, such as weak auto sales on Monday, indicate the confidence in a Trump-led economy has yet to translate into a tangible increase in demand.

As the bond market signals worry, stocks have largely held their ground, with the Nasdaq composite index hitting a new high as recently as Monday.

History shows something has to give.

Theoretically, let's say the 10-year yield was to drop another 30 basis points (0.3 percent) to 2 percent in the next month. Using hedge fund analytics tool Kensho, we found there were 35 times in the last decade when the 10-year yield dropped 30 basis points in one month.

The , on average, lost nearly 3 percent during those occasions, led by big losses in financials, materials and industrials.