The firm said in a research note that Tesla's Model 3 sedan is a "proven hit" and serious competition from other automakers for the plug-in auto market has not materialized, marking a sharp reversal from its previous stance.
The note came as Tesla moved up its quarterly earnings release date to Wednesday, in a move that hinted the California-based vehicle maker may be eager to share where it is on the road to profitability.
"Rumours of the Tesla killers have been as constant and unfounded as Bob Lutz's call for Tesla's bankruptcy", said Citron Research, founded by activist short-seller Andrew Left.
Over the past few months, Musk has faced a series of controversies linked to his activity on Twitter.
Left told Reuters: "I would not short this again".
The reversal does not necessarily signal a broader capitulation by Tesla's other short-sellers.
But Tamberrino reiterated his Sell rating for Tesla's stock and lowered his price target to $200 from $210, saying he is still bearish on the company's ability to produce profits over the long term.
He said the better sales number will be driven by higher-than-expected Model 3 average selling prices as consumers opt for higher-end options.
CCN reported yesterday that Musk made the tongue-in-cheek quip about offering bitcoin for sale in response to a question from a follower about whether Tesla accounts would soon begin utilising 2-factor authentication for added security.
Investors have been rattled by Musk's abrupt turnaround on his go-private plan and other recent behavior including smoking marijuana on a live web show.
Musk infamously tweeted in August that he was thinking about taking Tesla private, a move for which he was later penalized by the U.S. Securities and Exchange Commission for misleading the public.
Musk agreed to pay a $20m fine and step aside as Tesla's chairman for three years to settle charges that could have forced his exit from Tesla.
"While the media has been focused on Elon Musk's eccentric, outlandish and at times offensive behavior, it has failed to notice the legitimate disruption of the auto industry that is now being dominated by Tesla".