There's one silver lining in Wall Street investment banks' earnings reports

There's one silver lining for Wall Street banks that got killed on poor third quarter earnings results.

Investment banking revenue is matching or beating estimates, at a time when volatility is killing big bank earnings.

At Morgan Stanley, one of the few beats its various divisions posted was in investment banking. The bank missed third quarter earnings and revenue expectations Monday morning, sending shares down.

"The Firm benefited from the stability of the Wealth Management business, our ongoing leadership in Equities and the continued strength of our Investment Banking franchise," CEO James Gorman said Monday morning in the face of disappointing news.

Analysts polled by Bloomberg expected Morgan Stanley's investment bank revenue to be about $1.15 billion, and for the third quarter ending September 30, the bank posted about $1.3 billion at its investment banking division.

The same goes for JPMorgan: when Jamie Dimon's bank reported results last week, it missed analysts' earnings expectations. But JPMorgan beat estimates solidly for investment banking revenue, with $1.5 billion (expectations, according to Bloomberg, were closer to $1.4 billion).

Ditto for Goldman Sachs, which posted an awful third quarter earnings report. While the bank's stock was down on earnings results, its banking estimates were still in line with expectations.

But as long as bigger revenue drivers at banks, like equity sales and trading continue to get beat up in volatile markets, Wall Street's investment banks will keep facing headwinds.