I know this might not be a very quantitative question, but I figure this is the most relevant place to ask this.
Over that last few days, there has been a lot of news from the repo market, for example, https://www.bloomberg.com/news/articles/2019-09-17/with-repo-market-still-on-edge-fed-preps-second-blast-of-cash
Approximately half of the repo market is attributed to overnight repurchase agreements. What is the point of entering a repo agreement for such a short term? I have been able to find a lot of material with examples of two parties entering the agreement and explanations of how they work, but what is the motivation?
If I put up 100 million worth of treasury bills and in return, get cash and enter an agreement that I have to repurchase those bills the next day, what is the point of that cash? What can I do with that money in such a short time? Is it simply for some regulatory/filing purposes to show that you have cash on hand?