If you are interested in finance and economics and you want to do a PhD you need to decide whether you want to have EconPhD or PhD in Finance. Many universities have both degrees in their offer. In this post I will write why, in my opinion, going for an EconPhD seems to be a wiser route then pursuing FinPhD, even if you want to work in finance after completing your PhD program.
First, while doing a PhD in Economics you can write you thesis on financial topics. Economics Department are usually so large that you can find many finance oriented professors in them. To give an example in Department of Economics at Harvard University you have Andrei Shleifer, Efraim Benmelech, John Y. Campbell, Jeremy C. Stein, who are very much finance oriented. There are many other examples of top finance profs in top economics departments, so even if you are doing your PhD in Economics Department, you can write PhD thesis which are finance oriented. On the other hand, finance departments are usually quite small and don't give that kind of flexibility. It will be hard for example to diverge with your topic from pure finance to microeconomics during your PhD in Finance. Second, EconPhD gives clear signals. In all private and public organizations people know exactly what EconPhD is. They know what they should expect from EconPhDs. Finance PhD programs are less established and usually have shorter histories. Also curricula of different FinPhD programs differ considerably. Its not like EconPhD where you always have Micro, Macro, Econometrics plus some options. Every Finance PhD program is different. The only plus for Finance PhD, in my opinion, is that usually continuous time statistics (stochastic differential equations) is often a part of the basic curriculum. If you want to do research in finance during you EconPhD you have to learn it by your own.
Generally, EconPhD is a safer option. It is considered to be more general (and it is) , so in the future you can use it to find a job even if it is not finance oriented.