While Wall Street's largest stocks have tumbled since the decade that started Jan. 1, 2000, small-capitalization shares have seen a surge.

The Standard & Poor's 600, a small-stock index, soared almost 100% during the period, making a yearly profit of 7.1%. The large-cap S&P 500, by comparison, dropped roughly 18%, showing a loss of nearly 2% per year.

The small-cap Russell 2000 index reveals the same prototype. It outshined the big-cap Russell 1000 by almost 50 percentage points during the decade.

John Montgomery, President of Bridgeway Capital Management, a fund shop specializing in small-cap stocks says that the magnitude of the small-cap rally "has been breathtaking in pace and length".

And the style appears to be prevalent in the early months of this decade. Year to date, while the small-cap S&P 600 is soaring around 18%, the large-cap S&P 500 is upbeat less than 9%.

The question that is lurking in the minds of fund managers and shareholders is for how long the small-cap rule will continue.

According to Ned Davis Research, long durations of dominance aren't unheard of. Small caps outpaced big caps from 1974 to 1983.

However, the present bull market in small caps has set a record for time-span, The Russell 2000 hasn't noticed a 20% turn down relative to the large-cap Russell 1000 in over 3,660 days, dating back to April 17, 2000.