The part about trading not mattering to companies isn't true. One, companies issue additional shares after IPO. Two, the fluidity and likely future viability of

The part about trading not mattering to companies isn't true. One, companies issue additional shares after IPO. Two, the fluidity and likely future viability of the market affects IPO feasibility and price. Three, stock price affects employee compensation. Four, companies that own shares in other companies benefit from liquid markets just like retail investors. Corporate bonds also trade on the secondary market and that has similar consequences.