While famed German sandal maker Birkenstock is expanding in the city — it launched its first standalone US store in Soho last month — one heir to the hippie-chic brand is trying to decrease his own footprint.

Alex Birkenstock is dropping the price on one of his Financial District penthouses, which is now about to ask around $2.64 million — much less than its $4.49 million price tag in 2015.

Birkenstock bought the spread at 15 William St. for $2.72 million in 2009. Back then, though, the euro was stronger, a source close to Birkenstock quips, which means he could theoretically break even or even make money on the deal — in euros — even if he sells at a loss.

The two-bedroom, 2½-bathroom unit is 1,657 square feet and comes with a windowed kitchen, high ceilings, Brazilian walnut floors, a private terrace and East River views.

The building features a 30,000-square-foot amenity space, with a terrace, a 50-foot saltwater lap pool, a gym, a children’s playroom and a screening room, among other perks. The listing brokers are Platinum Properties’ Khashy Eyn and Cash Bernard.

Birkenstock also owns a brick-filled two-bedroom penthouse at the Setai Wall Street, which he bought for just under $6 million in 2011.

That unit, at 40 Broad St., is currently on the market as a $19,995-a-month rental.