It's been a crappy earnings season for the Dow

A research note circulated by Hans Mikkelsen of Bank of America Merrill Lynch pointed out that two of the most important US stock indexes, the Dow Jones Industrial Average and S&P 500, have recently come slightly unglued from each other.

Writing on Tuesday, Mikkelsen noted "US stocks declined following earnings misses from high profile Dow constituents IBM and [United Technologies], with the DJIA down 1% on the day compared with a loss of 0.43% for the S&P 500."

We can also add in Dow component Apple's 4% drop Wednesday after iPhone sales disappointed investors, making things even worse for the blue chip index. On Wednesday, the Dow closed down 0.38% while the S&P ended down a more modest 0.24%.

Because the Dow consists of just 30 stocks, an outsized move in any single component can have a much larger impact in the index than in the S&P, which consists of 500 stocks.

Mikkelsen included a chart showing that much larger drop in the Dow through Tuesday that we've updated to include Wednesday's closing values below.

Business Insider/Andy Kiersz, data from Yahoo Finance