Stocks continue to rise despite an unprecedented freeze in global economic activity and an oil-price crash, a divergence that makes some investors skeptical the gains can continue. The S&P 500 has baffled many investors by rebounding 27% since March 23 even as job losses have mounted. The broad equity gauge is now only down about 3% in the past year, with recent gains led byAmazon.com Inc. and Netflix Inc. Yet…