Behemoth at 4-8 East 94th Street Chopped To $49.95 M.

Last year, Richard Mack, an executive at the multibillion-dollar investment group Apollo Real Estate, which happens to be owned by his father, paid $23 million for Spence-Chapin's 24,463-square-foot headquarters at 4-8 East 94th Street. (It was built from three 19th-century row houses, which explains that address.)

Mr. Mack got permission from the Landmarks Preservation Commission in December to replace a homely three-story addition over one-third of the house with a full 60-foot penthouse, among other upgrades, then gutted the place, and then put the place back on the market for $59 million, $36 million more than he paid.

The tag just came down to $49.95 million, according to Ms. Chiang's Web site. Considering that no New York mansion has ever sold for more than $53 million (and remember that renovation costs at this triple-wide mansion may likely require well above $3.05 million), it's still a hefty tab. And of course the new tag is still huge enough to qualify for The Observer's 10 biggest listings list.

Then again, because the mansion is so hilariously wide, Mr. Mack is only asking $2,041 per square foot; by comparison, the $90 million duplex at 15 Central Park West wants $15,332 per square foot.