For many of the wealthy, 2012 is becoming a good year to sell.
They're worried about the "fiscal cliff," which is when tax cuts expire and spending cuts are set to go into effect at the end of the year.
Fearing an increase in capital gains and dividend taxes, many of the rich are unloading stocks, businesses and homes before the end of the year.
Wealth advisors say that with capital-gains taxes potentially going to 25 percent from 15 percent, and other possible increases in the dividend tax, estate tax and other taxes, many clients are selling now to save millions in taxes.
"Under almost any scenario, it makes sense to take the gains this year," said Gregory Curtis, chairman and managing director of Greycourt & Co. "Clients aren't selling willy nilly. But if they can and they have a huge gain, they're selling now."
If the Bush-era tax cuts expire, taxes on capital gains would revert back to its previous rate of 20 percent from its current 15 percent. Another 5 percent may be added from health-care levies and changes in itemized deductions, bringing the rate to 25 percent for many high earners.
Taxes on dividends could go from 15 percent to over 43 percent. And the estate tax could go from 35 percent on estates worth more than $5 million to 55 percent on estates over $1 million. (Read more: CEO Sends Out Raises, Not Pink Slips After Election)
As a result, the wealthy are taking a close look at all of their assets to see what could or should be sold off now to avoid potentially higher taxes next year.
The most noticeable sell-off has been in stocks. Wealth managers say many of their clients who have large gains on stocks are selling them now, or selling them or buying them back again to create a higher basis (and thus a lower tax bill later).
Since the wealthiest one percent of U.S. households control more than half of the stocks in the United States, their selling and buying can have strong ripple effects on the market.
Bankers say owners of private businesses are also pressing to sell their companies to ahead of a possible tax hike. If an entrepreneur, for instance, sells a company for $100 million, they could pay $10 million less in taxes than if they sold in 2013.
Deal advisors say that by selling his company to Disney this year for $4 billion, George Lucas potentially saved hundreds of millions of dollars in taxes.
Granted, business owners aren't suddenly selling their companies after the election. The businesses most likely to take advantage of lower taxes are small businesses that may have been in the process of selling and can push to close before Jan. 1.
"Selling a business is not easy, it's not like you can just pull a switch," said Frederic Seegal, vice chairman of Peter J. Solomon Co, the investment banking firm.
Mansion sales are seeing a similar acceleration, brokers say. Some recent multi-million-dollar sales in Florida, New York and California were partly driven by sellers who were anxious to sell before the end of 2012, brokers say.
The sell off could have profound impacts on both asset prices in the United States, as well as tax revenues. (Read more: Has Obama Been Good for Millionaires?)
Roberton Williams of the Tax Policy Center said the direct impact of all this front-loading is hard to determine, since there are so many other factors in the economy. But he said that a rise in wealthy sellers could put pressure on asset prices and stocks, at least in the short term.
"This could depress asset values," he said.
He also said that all this income-shifting could make revenues more volatile and unpredictable. It might also result in the government raising less than expected during the first year or two of the tax increase.
"The government may come out ahead this year, but lower the next year."
In 1986, for example, the capital gains tax rate was 20 percent but was schedule to go up to 28 percent in 1987 as part of President Ronald Reagan's tax overhaul. In 1986, capital gains collections soared to $52 billion – twice the amount as 1985. But the following year, when the higher rate kicked in, capital gains fell by 50 percent.
"Taxes are only one factor when it comes to decisions to gains," he said. "But they are certainly a factor."
-By CNBC's Robert Frank
Follow Robert Frank on Twitter: @robtfrank