Wall Street finance executives who were thinking of plunging some of their company's cash reserves into bitcoin got a heat check this week.

CFOs, not generally known as a risk-loving bunch, watched bitcoin sink more than 25 percent in a 24-hour period starting Sunday. Burning a hole of that size in the corporate rainy day fund would amount to a career-ending wipeout at virtually any S&P 500 firm.

Yet the cryptocurrency's 300 percent rally last year was hard to ignore, and a few companies dived in. MicroStrategy Inc. invested $425 million of its $500 million cash into bitcoin. In October, Square Inc., headed by longtime crypto advocate Jack Dorsey, announced that—as of the second quarter of 2020—it converted about $50 million of its total assets into the token. Proselytizers like Bill Miller of Miller Value Partners said this was just the start of what was sure to be a trend across Main Street.