Why might the stocks of small firms outperform large firms over long periods of time?Will this hold

Question:

Why might the of small firms outperform large firms over long periods of time?Will this hold over short periods of time, too? Plot since 1979 the stock indexes for small firms (FRED code: WILLSMLCAP) and large firms (FRED code: WILLLRGCAP) using annual data scaled to a common base year of 1979=100.

Stocks
Stocks or shares are generally equity instruments that provide the largest source of raising funds in any public or private listed company's. The instruments are issued on a stock exchange from where a large number of general public who are willing...