Which a company can provide by continuing to meet its planned objectives. If investors don’t like a companies strategic planning, they can either change the management, or sell their shares. If enough of the shareholders don’t like the management, and if there aren’t any investors available who do to buy their stake, then either it’s management or their planning will change. There a multiple ways for shareholders to exert their control over a company. There’s a huge pool of investors in the world, and they all want different things. Some of them will exert pressure to maximise short term returns, ohters won’t. The system itself does not intrinsically put any downward pressure on investment horizons.