Comment by sosilkj

a phd in physics can land you a job on a quant team at a bank or hedge fund or prop trading firm. another option could be "data scientist" roles (in a tech company or other industry). 'machine learning' roles also heavily favor someone with masters/phd.

for banks/hedge funds/etc roles, look at the book "Capital Markets for Quantitative Professionals" to get up to speed on background knowledge.