The gap between returns on corporate capital and government bond interest rates

Looking at the United States and the euro zone, we note the gap between return s on corporate capital and long-term government bonds interest rates has become very wide. This gap may have three causes: The presence of monopolies, or companies with dominant positions, which reduce their investment abnormally ; A sharp rise in the corporate risk premium; Simply a financial anomaly or imperfection with a lack of arbitrage. How to respond in each of the three cases? If there are monopolies, competition must be restored; If there is a high risk premium, there is no anomaly and no response is needed; If there is a financial imperfection, it will lead to too much public investment and too little private (corporate) investment: the government must then borrow to stimulate corporate investment.