英语翻译

英语翻译
原句：“economists say families about to go into debt to fund four years of partying,as well as studying,can console themselves with the knowledge that college is an investment that,unlike many bank stocks,should yield huge dividends.”
我想问下这里“should yield huge dividends”的逻辑主语是谁,college or stock?
假如主语是college,我在should前面加个which,能不能使得主语变成stock.
我现在要把这句的意思变为：“上大学是种投资，它不像股票那样应该产生巨大的收益”即，股票能产生巨大收益，而上大学不像股票，所以上大学不应该产生巨大的收益。如果要把意思变成这样，应如何改？这样改可否“college is an investment and it is unlike stocks which should yield huge dividends”。