With the highest brackets not being over 50%, I would think someone would almost have to try to get the rate that high. Although the article doesn't provide a lot of information about how the number is calculated, it looks like there are a few issues going on:
-he lives in NYC, so they are counting the high state and local taxes in NY and NYC in addition to Federal.
-they are talking about his tax bill on the post-deduction income. Ex: He is earning $100, paying $80 dollars in mortgage interest, donations to charity, interest on his margin trading, etc, and then his tax bill is $21 out of the $20 dollars left over after the deductions.
Regardless of the above items, the number still makes for an interesting article. Even if his specific issue is related to the large number of deductions he can take, I'm glad taxes have come up again in this election season as it's an area that sorely needs to be overhauled.