This is going to seem like a really stupid question...but how do companies benefit from a higher SP?
Let's just say a company floats and sells 100 shares at $1 each. People buy these shares, so the company gets $100 in return. Tommy has bought 5 of these shares. When trading commences, someone buys these 5 shares off him for $2 each, so Tommy has made a profit of $5. That profit has gone to Tommy, not the company.
So how has the company benefited from a higher SP?