In two consecutive record-breaking deals, Kayak co-founder and chief executive Steve Hafner has paid $40 million for a penthouse on Fisher Island after selling his smaller unit at L’Atelier Miami Beach for $36 million.  

On Friday, Mr. Hafner closed on the sale of his duplex at L’Atelier Miami Beach after listing it for $39.9 million in March. The deal was the priciest Miami-Dade County condo sale of the year so far, according to local luxury agent Danny Hertzberg of Coldwell Banker Realty in Miami, who wasn’t involved in the deal. 

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Palazzo Della Luna on Fisher Island.

PHOTO: KRIS TAMBURELLO/PALAZZO DELLA LUNA

Then, later that evening, Mr. Hafner broke his own record with his purchase of a roughly 10,000-square-foot condo at the Palazzo Della Luna on Fisher Island. The seven-bedroom home went on the market for $48 million in April after first listing for $40 million in 2018

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“We loved the L’Atelier community,” said Mr. Hafner, 53. However, “we needed to move closer to our kids’ school on Fisher Island.”

Douglas Elliman agent Oren Alexander represented the buyer of the L’Atelier penthouse, but declined to identify his client. 

Fisher Island is a 216-acre private island south of Miami Beach that is home to about 800 families of CEOs and entrepreneurs. Mr. Hafner’s new home at the Palazzo Della Luna is on the 10th floor with multiple terraces and a rooftop patio with a pool, according to the listing. 

At L’Atelier Miami Beach, Mr. Hafner bought his six-bedroom unit for $21 million in 2017 while the building was under construction. Mr. Hafner and his wife, Staci Hafner, 41, redesigned the roughly 8,000-square-foot unit with Bart Reines Luxury Home Builder. 

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The penthouse has a glass elevator, a private 40-foot infinity pool, and a summer kitchen and bar. L’Atelier was developed by SMG Management and W Capital Group, according to the website.

Mr. Hafner co-founded Kayak Software Corporation, an online travel booking tool, in 2004, according to the company’s website. The company was acquired by Booking Holdings in 2013 for $1.8 billion, the company said. Mr. Hafner, who also has homes in Rowayton, Conn., and the Hamptons, sold his Chelsea condominium for $23.5 million earlier this month, according to property records.

“We haven’t been in our NYC [apartment] since Covid and didn’t see a path to ever getting back there,” said Mr. Hafner.

Until now, the county’s highest-priced condo deal of the year was a penthouse at Continuum, which sold for $35 million in April, Mr. Hertzberg said. The highest-priced condo sale on record was the 2015 double penthouse sale at Faena House for $60 million. 

Miami Beach luxury condos sold for an average of $4.34 million in the third quarter of 2021, up 8.8% from the same time last year and 47.94% from the third quarter of 2019, according to a report by Douglas Elliman. The number of sales rose 96.1% compared with the third quarter of 2020 after staying steady from 2019 to 2020. Inventory fell for the fifth consecutive quarter, according to the report. 

Eloy Carmenate and Mick Duchon of the Corcoran Group represented Mr. Hafner in the L’Atelier sale. Dora Puig is the director of sales and marketing for the Palazzo Della Luna.