  We investigate the impact of the COVID-19 pandemic on the betting markets of
professional and college sports. We find that during the pandemic, the
moneyline betting markets of the National Basketball Association (NBA) became
very inefficient. During this period, if one bet uniformly on underdog teams in
the NBA, one could achieve a 16.7% profit margin. It is hypothesized that this
inefficiency is due to the absence of live audiences during the NBA games. Such
inefficiencies are not seen for any other sport. Much of the inefficiency comes
from a small fraction of games with moneyline odds in the 233 to 400 range. We
find that with clever strategies, one is able to achieve a 26-fold gain on an
initial investment by betting on NBA underdogs during this time period.
