Authorities investigating timely trading in Activision Blizzard Inc. securities are looking into at least one meeting between the videogame firm’s chief executive and one of three traders days before they placed a large bet on Activision shares, according to people familiar with the matter.

Activision CEO Bobby Kotick met with Alexander von Furstenberg in the week before Mr. von Furstenberg and media moguls Barry Diller and David Geffen bought options to purchase Activision shares at $40 each on Jan. 14. The options trade, which has generated an unrealized profit of about $59 million, was arranged days before Activision agreed to be acquired for $95 a share by Microsoft Corp. , The Wall Street Journal has reported.

The Justice Department is investigating whether the options trade violated insider-trading laws, the people familiar with the matter said. The Securities and Exchange Commission is separately conducting a civil insider-trading investigation, the people said.

Mr. Diller previously told the Journal in an interview that none of the men had material nonpublic information about the Microsoft-Activision deal. He confirmed they had been contacted by regulators.

“We had zero knowledge of that transaction and it belies credulity to think that if we did we would have proceeded,” Mr. Diller wrote Thursday in an email to the Journal. “It’s equally unlikely to believe Mr. Kotick, a sophisticated professional, in a social breakfast with Mr. von Furstenberg and his wife would have told them of the pending transaction.”

Mr. von Furstenberg disclosed his breakfast meeting with Mr. Kotick to law-enforcement authorities who interviewed him about the trade, according to a person familiar with the matter. Messrs. von Furstenberg and Geffen haven’t responded to the Journal’s requests for comment.

Alex von Furstenberg disclosed his meeting with Mr. Kotick to law-enforcement authorities who interviewed him about the trade, according to a person familiar with the matter.

Photo: Drew Angerer/Getty Images

Mr. Kotick’s status in the investigation couldn’t be learned. He hasn’t been interviewed by law-enforcement authorities, some of the people said. The Justice Department declined to comment. The SEC declined to comment.

“Mr. Kotick had a social brunch with his friends at a popular restaurant,” an Activision spokesman said. “He, of course, didn’t share any information with them regarding a possible transaction with Microsoft.”

The meeting between Messrs. von Furstenberg and Kotick adds to the growing regulatory pressure on Activision and Mr. Kotick personally. The SEC is separately investigating Mr. Kotick and other Activision executives over how they handled workplace misconduct allegations, the Journal has reported, citing documents and people familiar with the investigation. That probe, along with an investigation led by the California Department of Fair Employment and Housing, has escalated since the Microsoft deal was announced. Activision has said it is cooperating with the SEC probe and has called a recent move by the California state agency to subpoena police records “an extraordinary fishing expedition.”

Mr. Kotick and Activision have been under intense scrutiny from employees, investors and regulators since a July lawsuit from the California state agency that alleged a culture of sexual harassment and gender pay disparity. Soon after the Journal reported in November that Mr. Kotick knew of some sexual harassment claims and didn’t report them to Activision’s board of directors, Microsoft reached out about a possible deal, the Journal has reported. Mr. Kotick has said he has been transparent with his board of directors, and Activision has called the Journal’s reporting “misleading.”

On Wednesday, a federal judge approved an $18 million settlement between Activision and the Equal Employment Opportunity Commission, which has been investigating Activision since 2018.

Experts said regulatory investigations are unlikely to derail the deal with Microsoft unless there is a so-called material adverse change that would affect the value of the deal, which is expected to close sometime next year. Mr. Kotick isn’t expected to remain at Microsoft, people familiar with the matter said.

Microsoft is required to pay Activision a breakup fee of about $3 billion after April 18, 2023, if Microsoft walks away from the deal, securities filings show. If Activision abandons the deal, it must pay about $2.3 billion.

Barry Diller has said that none of the men had any material nonpublic information about the Microsoft-Activision deal ahead of the options trade.

Photo: Nikki Ritcher for The Wall Stree

Mr. von Furstenberg arranged the options trade through

JPMorgan Chase & Co. for himself and Messrs. Diller and Geffen, according to some of the people familiar with the matter. Mr. Geffen believed Activision was undervalued and would be acquired or taken private, and first contacted Mr. Diller with the idea for the trade, according to Mr. Diller.

“It’s a simple situation and a simple coincidence, which took place over 2 business days,” Mr. Diller wrote in the email. “All the information and records we are giving to the investigators will support that. I did not wait until I was 80 to participate in so obvious a fraud.”

Mr. von Furstenberg is Mr. Diller’s stepson, and Messrs. Diller and Geffen are longtime friends. Mr. Kotick is a longtime friend of Messrs. Diller and von Furstenberg, according to people familiar with their relationship.

Activision shares were around $63 at the time of the trade, meaning the options already were profitable to exercise, or “in the money.” Options holders stood to reap more if Activision’s stock price rose.

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Mr. von Furstenberg is the founder and chief investment officer of Ranger Global Advisors LLC, a company that manages his family’s fortune, according to his LinkedIn profile and Ranger’s website. The firm manages more than $1 billion, the website says. An officer of Ranger Global Advisors declined to comment.

Call options give a trader the right to buy shares at a specific price by a certain date. The three men have yet to exercise the options, which don’t expire until early next year, the people said.

Traders using options are often looking to profit from a swing in share prices. Because options typically cost less than shares, they can amplify gains when traders bet right, particularly when they purchased options that were “out of the money”—the term for bets that aren’t profitable at the time the options are purchased. Options that are “in the money” at purchase tend to be more expensive and less risky because they can be immediately profitable to exercise.

The traders appear to have spent around $108 million to acquire the right to buy 4.12 million Activision shares, the people said. Those options if exercised today would be worth around $167 million, based on recent trading prices.

The value of the options would rise further if the deal closes at the stated per-share price of $95, which Microsoft has said is expected after midyear, compared with Activision stock’s Wednesday closing price of $80.36. If the men hold the options through a closing at that price, their profit stands to surpass $100 million, the people said.

Write to Dave Michaels at dave.michaels@wsj.com and Kirsten Grind at kirsten.grind@wsj.com