The Dow Jones Industrial Average briefly hit an intraday record high on Monday before diving into negative territory as investors grew increasingly concerned that tightening restrictions in New York City and elsewhere could weigh down the economy. The Dow hit an intraday record high of 30,325 after the first hour of trading but slumped through the rest of the day as positive news on the vaccine rollout was offset by news that further restrictions will crimp business in the weeks before Christmas. New York City Mayor Bill di Blasio said that the city could need to go into ‘full shutdown’...