Thursday's 10% plunge in the Dow Thursday on coronavirus fears was its worst day since the 1987 "Black Monday" market crash. Some analysts are wondering whether the market will look as similar to that period on the way back up, as it has on the way down.
Market strategists looking for historic similarities are finding some with 1987, though the causes for the sell-off are nothing alike.Â
 In 1987, stocks were selling off because of a potential tax on mergers and the biggest one-day decline ever on Oct. 19 that year was exacerbated by electronic trading in an era before circuit breakers.
"In 1987, the decline took longer but from when it really started cascading lower, it only took 10 days," said Matt Maley, equity strategist at Miller Tabak. The market top was in August, 1987.
For sure, strategists say without the type of circuit breakers in place in the market now that decline could have been much steeper.
 The S&P 500 fell 9.5% Thursday and was about 29% off its high.
James Paulsen, chief investment strategist at Leuthold Group, said there are other  similarities in the two periods.
"In both cases, the economy was at or near full employment and generally healthy going into the crash. Both suffered severe and amazingly quick collapses and… both have very similar patterns leading up to and during the crash.  After the 1987 capitulation, there was also widespread calls for an imminent recession as there are today," he said in a note.
Paulsen said it's not clear how the virus will impact the economy.Â
Source: Leuthold Group
"Who knows how the contemporary crisis will play out, but it is worth thinking about its similarity to another quick moving and very scary market collapse when a recession did not occur and which recovered by almost 30% from its low within the next year and rose to a new high within about 18 months," he wrote.
He said while the causes of the selling are different, the swift drop and widespread panic are similar.Â
Maley said the 1987 crash was not an economic event at all.Â
"The whole thing was kicked off by a trial balloon set up to put a bigger tax on takeovers that were taking place at the time," Maley said.
Investors were also using portfolio insurance, or options that resulted in creating more forced selling.
"You had a perfect storm. But people weren't afraid about a recession," Maley said. "Now people are selling for an economic reason. They're worried about the coronavirus causig a recession and the oil market causing stress in the credit market."