A mystery Microsoft mogul has been quietly assembling the priciest Palm Beach estate near Mar-a-Lago

In a string of blockbuster deals unfolding just north of Mar-a-Lago, a mystery buyer linked to Microsoft has quietly assembled what could become one of the most valuable private estates in the U.S. — a sprawling oceanfront compound in Palm Beach with an estimated price tag between $250 million and $350 million, according to reporting from The Wall Street Journal and The Real Deal.

The buyer — whose identity remains unconfirmed but is widely rumored to be Microsoft billionaire Charles Simonyi — has spent the past several months scooping up prime properties on North Ocean Boulevard.

According to the Journal, the buyer paid roughly $250 million across four separate deals, while The Real Deal pegs the total value closer to $350 million.

The core of the assemblage comprises two rare oceanfront lots at 1063 and 1071 N. Ocean Blvd., previously owned by cosmetics heir William Lauder.

Together, the 2.3-acre parcels offer 360 feet of beach frontage. Lauder, who initially intended to keep the land for personal use, had listed the properties for a combined $177.8 million.

Sources told TRD the sale went through in February via a transfer of LLCs, rather than a deed, for more than $160 million.

In June, the same buyer picked up two non-oceanfront homes across the street in separate off-market transactions.

A Delaware entity called Creekshore LLC acquired a 3,600-square-foot home at 1066 N. Ocean Blvd. from former Hearst executive Cathie Black and her husband, attorney Thomas Harvey, for $18 million.

The couple had bought the property for $4.2 million in 2018.

In an email to the Journal, Harvey said he did not know the “true identity of the buyer,” adding that the offer was unsolicited.

Next door, another Delaware LLC named Mango Leaf paid $30 million for a 5,800-square-foot home at 1072 N. Ocean Blvd., which last sold for $5.3 million in 2017. Both sale prices far exceeded market value, local brokers told the Journal.

Altogether, the assemblage now spans nearly 4.2 acres. If completed as rumored, it would rival Palm Beach’s most legendary compounds.

Billionaire Ken Griffin holds the current record with a 19.3-acre estate assembled for $350 million and expected to be worth over $1 billion upon completion, The Post previously reported. Amazon founder Jeff Bezos, meanwhile, has spent about $234 million on Indian Creek Village properties in nearby Miami.

While the buyer remains publicly unidentified, incorporation records reviewed by the Journal show ties to Greyson Blue, a Seattle-based attorney with K&L Gates who previously worked for the Gates Foundation.

Blue’s name appears in the registration of the Delaware entities used in the deals. He did not respond to requests for comment. A person close to the Gates Foundation told the Journal that Bill Gates is not behind the purchases.

Simonyi — credited with creating Microsoft Word and Excel — has an estimated net worth of $8.2 billion, according to Forbes. Sources told TRD he is likely the buyer. Other names floated include former Microsoft CEO Steve Ballmer, whose net worth exceeds $140 billion, and Gates himself, whose daughter Jennifer Gates has owned a $33 million equestrian compound in nearby Wellington.

Despite the buyer’s aggressive push, not every property on the block has been secured.

Rock legend Jon Bon Jovi, who owns the mansion at 1075 N. Ocean Blvd., has so far rebuffed offers.

“We just don’t have these kinds of large properties available for sale,” said Dana Koch of the Corcoran Group, speaking to the Journal. “After buying all of these properties at a mind-boggling number, [the buyer] is protecting his investment and affording himself even more privacy.”

Bon Jovi paid $43 million for his 0.7-acre estate in 2020. Records show the 10,000-square-foot home includes six bedrooms, a wine cellar and a gym.

Sources told TRD that the buyer is also eyeing the neighboring property at 1055 N. Ocean Blvd., owned by real estate investor William Rickman Jr., who purchased the 1930s-era home for $13.1 million in 2016.