Virus winners

Costco jumped 8.9% to $306.29 and Walmart rose 6.5% to $114.67 Monday on prospects of a revenue boost as shoppers stocked up on everyday goods as fear over the coronavirus' spread hits consumers. Costco shares closed the week at $311.34; Walmart closed at $117.23.

Virus losers

Norwegian Cruise Line dropped 7.4% to $34.50 and Carnival fell 3.7% $32.21 Monday as the outbreak has led to canceled flights and disrupted vacation plans. Norwegian Cruise Line closed Friday at $27.10.; Carnival closed at $27.15.

Less traveled

Payments processor Visa declined 2.4% to $187.76 Tuesday after warning investors it expects first-quarter revenue to suffer because of the damage to international travel due to COVID-19. Shares closed the week at $184.36.

No slack for Slack

Slack Technologies, Inc. shares fell 6.9% to $26.42 Friday after surging nearly 40% in recent weeks on prospects of a revenue boost for the work-based communication tech firm as more people work from home because of COVID-19. Slack shares had been resistant to losses in the market sell-off of the past two weeks.

Biden bounce

UnitedHealth Group shares rose 8.8% to $284.44 Wednesday as health care stocks rose after a strong performance by Joe Biden in state primaries on Tuesday moved him to top-tier status for the Democratic presidential nomination. Many investors believe he is more friendly to businesses than the other top contender, Bernie Sanders, whose proposals for health care and the economy could hurt profits at insurers and other companies. Shares closed Friday at $283.87.