A discontinued Rolex just sold at auction for a record-breaking $2.5 million — the winning buyer reportedly was the watchmaker

• A rare Rolex Milgauss "mad scientist" watch sold at auction for $2.5 million.
• The winning buyer purchased the timepiece on behalf of Rolex itself, sources told Bloomberg.
• Watchmakers occasionally buy copies of their own products for historical purposes.

A rare Rolex Milgauss steel sport watch sold for a record-setting $2.5 million at auction in Switzerland on Saturday.

Dubbed "The Pinnacle," the 1958 watch features the line's original rotating bezel, honeycomb dial, and lightning bolt second hand, and was estimated to be worth roughly $1 million before the bidding began.

The winning buyer was acting on behalf of Rolex itself, sources told Bloomberg. It's not uncommon for watchmakers to buy copies of their own products for historical purposes, the outlet noted. Insider was unable to reach Rolex for comment.

Earlier this year, the Swiss brand quietly discontinued production of the Milgauss, known to many as Rolex's "mad scientist" watch for its magnetic interference-resistant design.

The Milgauss was designed in consultation with the world's top nuclear physicists at the Conseil Européen pour la Recherche Nucléaire, or CERN, in Switzerland. Its mechanical movement, which ordinarily might be thrown off by the magnetic fields surrounding high-powered lab equipment, is protected by a special cage within the watch case.

Original versions of the Milgauss are hard to find, since the line was previously discontinued in 1988 for about 20 years, according to leading Rolex reseller Bob's Watches. The newest generation retailed for $9,300, and now sells on the resale market for a few thousand dollars more.

Even with a record-setting sale, "The Pinnacle" was outmatched at the same auction by a gem-encrusted, yellow gold Cosmograph Daytona, which gaveled for $4.1 million.

The world record auction price for any wrist watch remains $17.8 million in 2017 for Paul Newman's very own Daytona Reference 6239.