在CFA2 Book3股利折现估值一章的最后，介绍公司持续增长率 SGR = RR*ROE，进而有这样一句话“ if the actual growth rate is forecasted to be greater than SGR, the firm will have to issue equity unless the firm increases its retention ratio, profit margin, total asst turnover, or leverage".   

为何实际增长率大于SGR，则公司需要考虑发行股份呢？实际估值与操作中，可以用该方法预测公司发行股份的动机么？希望大拿赐教！