As US home prices have climbed to within a hair's breadth of their all-time highs from 2006, we've asked time and time again whether this is a market "top" or a "breakout".

In each case, we've pointed to slackening transaction volume in some of the hottest housing markets in the US as a sign that, despite a purported paucity of new housing stock during the post-crisis era, high prices have left much of the market out of reach for middle- and working-class Americans (even those who might consider themselves part of the upper-middle class) as asset price appreciation has far outstripped wage growth.

And nowhere has this trend been more visible, perhaps, than in Manhattan.

To wit: After months of declines, Apartment sales in Manhattan fell in January to the lowest monthly rate since February 2012 (a six year low) as a trend in both declining sales prices and volume has intensified.