So a gym buddy asks me whether it’s time to sell

Hell, I don’t know.

But I can think of several reasons that Tom, who lives on Riverside Drive on Manhattan’s Upper West Side, should consider the possibility:

• He also wants to buy, and buying and selling in the same market usually is a wash.
• Two reasons that selling may not be a wash is that he also is trading up:  1.  Apartments above $1 million tend these days to go for deeper discounts than those at lower prices; 2.  If the percentage discount is the same for both properties, the dollars saved on the bigger apartment will be more than those lost on the smaller unit.
• Prices may or may not fall farther.