The fast-spreading coronavirus has prompted even the biggest U.S. companies to cut their spending and bolster their balance sheets, proving once again how cash is king, especially in times of crisis.

After a decadelong U.S. economic expansion, not every company has entered this crisis with the same cash cushion. Apple Inc. ended the year with $247 billion in cash, securities and account receivables, enough to run its operations for more than a year even if it didn’t cut costs or sell a single iPhone. Discount retailer Dollar...