Scott Sumner makes a good point against the claim in a news report based on an economic study that "the rich got richer" in 2012 as they sold stock ahead of an expected increase in the capital gains tax: "it claimed that America's richest got much 'wealthier' in 2012 by selling stocks ahead of the tax increases. Seriously."
While the sale of long-held stock and the accompanying recognition of capital gain income (and payment of capital gain tax) may make it look like the rich are getting "richer" because they are recognizing more income, in fact someone who sells stock and pays taxes doesn't end up any richer at all. They end up poorer (if you hadn't counted the future tax obligation as a liability), or the same (if you had counted the future tax obligation as a liability)
Mr. Sumner's complaint is against NPR, but the New York Times made a similar error in its headline.