The law requires that the executive board to provide value to shareholders (valuation or dividends). This usually translate in quarter reports with good numbers for greater valuations. It's known that this requirement and tradition skews boards to short term goals which can damage companies' future.
This is the good scenario, just a skew for short term goals.
The bad scenario is when the quarter reports look good my quasi-illegal number juggling and also legal practices which should be illegal like a company buying it's own stocks to please shareholders.
Currently this even worse because central banks interventions from low interest rates (it has been cheaper for a company to use debt buy it's own stocks than to invest) to central banks buying stocks and causing inflated valuations.