I have a piece of exercise requesting me to make sentences about a businessman's changing fortunes. There are some of these sentences:
Alexander won a small fortune in a casino when his luck was good. Alexander lost a fortune in a business that went bankrupt.
I think that the two fortune in these two sentences mean an amount of money, but I don't think fortunes means amounts of money in the phrase changing fortunes. I've seen a lot of news' titles contain changing fortunes and there are even a book named this phrase. What does it mean in the request of my homework?