Cost of New Common Stock. Indi Co's common stock is selling for $50. Last years dividend was $4.8 per share. Compute the cost of retained earnings (or internal equity) if both earnings and dividends are expected to grow at zero percent.Marist Co.s common stock is selling for $50. Last years dividend was $4.8 per share. Compute the cost of retained earnings (or internal equity) if both earnings and dividends are expected to grow at a constant rate of 9 percent.