While the direction of the market still hinges on when the coronavirus outbreak is slowed, some signs are emerging that the bulk of the selling in stock and corporate bonds is behind us, according to Bank of America's Chief Investment Strategist Michael Hartnett.

First is the sheer magnitude of the pullback. More than $20 trillion in U.S. stocks value was wiped out during the pandemic-induced sell-off, and investment-grade credit spreads have widened to 400 basis points from 100 basis points, Hartnett said.

"Tough for asset prices & volatility to subside until human beings can safely leave their homes; that said ... lows on corporate bond & stock prices are in," wrote Hartnett, whose straightforward and data-filled notes are popular on Wall Street.

Secondly, a powerful contrarian "buy" signal for the market has been triggered. Bank of America's proprietary "Bull & Bear" indicator, which looks at recommended positioning of Wall Street, points to "extreme bear."

The past four weeks have seen a record $284 billion outflows from bonds and $658 billion in to cash, Hartnett added.

The indicator shows investors' recent exit from stocks and corporate bonds is overdone, Hartnett said, adding the extreme bearishness always leads to big bounces.