The tech billionaire Elon Musk on Wednesday walked back his baseless claim that a British diver involved in the cave rescue efforts in Thailand was a pedophile, an accusation made after the man criticized a submarine that Mr. Musk had said he built to help with the rescue.
The cave diver, Vern Unsworth, who helped with the effort to rescue 12 boys and their soccer coach, had told CNN last week that the miniature submarine, built with rocket parts, was a “P.R. stunt” and that Mr. Musk could “stick his submarine where it hurts.”
That drew an angry response over the weekend from Mr. Musk, who called Mr. Unsworth a “pedo guy” in a series of angry tweets defending the vessel.
The posts by Mr. Musk, which were later deleted, reverberated beyond social media. The news spooked investors and contributed to a slide on Monday in the stock price of the electric car company Tesla, for which Mr. Musk serves as chief executive. Tesla stock climbed again on Tuesday.
Mr. Musk apologized in tweets responding to an article that said the media had overplayed his involvement in the rescue effort, writing, “As this well-written article suggests, my words were spoken in anger after Mr. Unsworth said several untruths & suggested I engage in a sexual act with the mini-sub, which had been built as an act of kindness & according to specifications from the dive team leader.”
He added: “Nonetheless, his actions against me do not justify my actions against him, and for that I apologize to Mr. Unsworth and to the companies I represent as leader. The fault is mine and mine alone.”
The submarine was not used in the rescue, and Thai officials had previously called it impractical for the mission in the Tham Luang Cave.
Mr. Musk’s attack on Mr. Unsworth drew criticism from investors like Gene Munster, head of research at the investment firm Loup Ventures, who wrote in an open letter on Monday that the exchange “crossed the line.”
Calling on Mr. Musk to apologize, Mr. Munster added: “I suspect you would agree given you deleted the string from Twitter, but it will take more than that to regain investor confidence. Your behavior is fueling an unhelpful perception of your leadership — thin-skinned and short-tempered.”
In an interview Wednesday, Mr. Munster said that Mr. Musk’s apology was a “huge first step,” but that Mr. Musk would have to continue to be measured on social media. Loup Ventures does not invest in Tesla.
“I can see why somebody would say it’s an 80 percent apology,” Mr. Munster said, adding that it was rare for Mr. Musk to publicly apologize. “I’m not aware of him ever doing it.”
It was not the first time Mr. Musk’s anger has drawn public criticism. In an earnings call in May that was mentioned in Mr. Munster’s letter, Mr. Musk cut off an analyst asking about Tesla’s need to raise additional money from investors, saying that “boring, bonehead questions are not cool.”
Mr. Unsworth, who lives in Thailand and had previously explored the cave the soccer team was trapped in, has been quoted in news reports as saying he might pursue legal action against Mr. Musk. He could not be reached for comment on Wednesday.
“I think people realize what sort of guy he is,” Mr. Unsworth told an Australian news outlet this week. “It’s not finished.”
A spokesman for Mr. Musk said he and his representatives had no further comment about the apology or investor concerns.
The 12 members of the Wild Boars soccer team were released from the hospital on Wednesday. Along with their coach, they had been trapped in the cave since June 23 by waters that rose nearly 10 feet in less than an hour.
They were rescued from the flooded cave last week, a complex and delicate feat conducted by a rescue team of divers as oxygen dwindled and the soccer team was in mortal danger.
Mr. Musk was in Thailand during the rescue efforts to deliver his submarine. He and his representatives have maintained that the submarine would have been usable.
A Thai Army official said last week that the mini-submarine would be appropriate for use in open water and that he had heard the technology would be given to the Thai Navy SEAL team.