The Wall Street Journal reported that US companies are buying back their shares at an aggressive pace. Announced buybacks have surged since the US passed a $1.5 trillion tax cut in December, exceeding $200 billion in the past three months. Some of the biggest buyers include Cisco Systems, at $25 billion, Wells Fargo, at about $21 billion; and PepsiCo, at $15 billion. Clearly, these companies know something that convinced them that buying their own stock is a good investment. A clue for the market?