(Bloomberg) -- Biotech’s biggest short bet, vaccine developer Moderna Inc., broke another intraday record for a fourth straight session Tuesday, with one Wall Street strategist comparing the biotech’s volatile trading to bitcoin’s wild swings.Moderna jumped as much as 17% shortly after the market opened Tuesday before nose-diving 10% in the afternoon session. The stock had surged 55% and added more than $21 billion in market value in the prior three trading days after the company revealed positive data and plans to file for approval of its experimental Covid-19 vaccine.“Vaccine stocks trading more like bitcoin than biotech,” Jared Holz, a Jefferies health-care equity strategist wrote in a note to clients. The “unprecedented” moves are likely driven by retail investors and potentially quant models rather than institutional investors, he said as the stock blew past the 12-month price target of all but one analyst.S3 Partners data show Moderna’s short interest is $3.55 billion with 23 million shares shorted. That may lead some to blame part of the gains on short covering, where bearish bettors buy back borrowed stock to close their positions. Holz says that short interest levels are “not nearly high enough to be generating this type of trading action” after Moderna’s stock added at least 10% a day over the past few trading sessions and more then doubled in November.Ihor Dusaniwsky, S3’s managing director of predictive analytics, agreed that short covering wasn’t driving the move with trading volume far exceeding short-side activity. Over the past 30 days, 4.33 million shares worth $302 million were covered, he said. Short-sellers are down $3.09 billion this year in net-of-financing mark-to-market losses with $2.03 billion of that coming in November, he said.‘Vast Majority’The leading shots, including Moderna’s and one from Pfizer Inc. and partner BioNTech SE, use a technology known as messenger RNA. AstraZeneca Plc’s experimental vaccine uses a harmless virus to generate an immune response.“Investors now believe mRNA vaccines will take the vast majority of the U.S. market given growing investor concerns around adenovirus vaccine and in particular the recent AstraZeneca data,” Morgan Stanley analyst Matthew Harrison wrote in research note. Investors may be expecting as much as $15 billion in sales from the Cambridge, Massachusetts-based biotech’s Covid-19 inoculations over the next two years, but its the revenue after 2022 that is sparking the most debate, he said.Bears are expecting multiple vaccines and cheaper pricing while bulls expect higher pricing to prevail after the pandemic winds down. Harrison, who has an overweight rating on Moderna, was bullish on the opportunity for booster shots and the rest of Moderna’s pipeline, though his price target remains $100.The stock dropped to a session low on Tuesday while management was presenting at the Evercore ISI Annual HealthCONx Conference.Earlier Tuesday, European regulators said they would finish assessing Moderna’s shot for a conditional authorization by Jan. 12 while Pfizer Inc. and partner BioNTech SE should get a decision on their shot by Dec. 29.(Updates to add share reversal)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.