  We describe and document three mechanisms by which corporations can influence
or even control stock prices. (i) Parent and holding companies wield control
over other publicly traded companies. (ii) Through clever management of
treasury stock based on buyback programs and stock issuance, stock price
fluctuations can be amplified or curbed. (iii) Finally, history shows a close
interdependance between the level of stock prices on the one hand and merger
and acquisition activity on the other hand. This perspective in which Boards of
Directors of major companies shepherd the market offers a natural
interpretation of the so-called "herd behavior" observed in stock markets. The
traditional view holds that by driving profit expectations, corporations have
an indirect role in shaping the market. In this paper, we suggest that over the
last decades they became more and more the direct moving force of stock
markets.
