They say timing is everything, but investors who have applied this notion to making investment decisions have found that in the market, not everything can be timed.
The idea is certainly appealing: Buy an investment at or near the trough, sell at or near the peak, and move on to the next one.
The problem is only in hindsight are those peaks and troughs clearly visible. And numerous research studies over many periods back up what seems only obvious: Markets move too sporadically and trends are too unpredictable to be consistently exploited by market timers.
Unfortunately for their wealth, most investors haven’t learned this lesson. New data by USA TODAY and online portfolio tracking service SigFig show how much active traders continue to leave on the table. 
SigFig, which tracks over $40 billion in assets held in individual brokerage and 401(k) accounts, groups investors based on their degree of portfolio turnover (trading): “Buy and Hold” investors traded the least, with less than 10% turnover; “Active” investors had between 11% and 50% turnover; “Very Active” traders experienced 51% to 100% turnover; and “Aggressive” investors were the most frenetic traders, turning over their portfolios more than 100%.
How are these investors doing?
Not good—the more “active” the trader, the worse their performance.
For the six months ended September 30, “Buy and Hold” investors lost, on average, 1.7%. “Active” investors were down 7.5%, “Very Active” traders lost 6.5%, and “Aggressive” investors—the most active of all categories—were down the most: 11.8%.
The results speak for themselves. Investors without a disciplined, long-term plan fall prey to their own impulses and the chorus of media voices regularly telling them to “do something!”, even though it’s often better to do nothing.
Activity clearly doesn’t equal value.
 “How we’re performing”. USA TODAY, October 3, 2012.