OPT for MS after getting an OPT for PhD

As a PhD student, I have applied for a pre-completion OPT and unfortunatelly I had some bad luck and could not use it.

What is unusual in my case is that while I am still completing my Economics PhD program, I am also earning a Master’s degree in Statistics at the same time.

Can I successfully apply for a post-completion OPT for MS in Statistics, given that Statistics is STEM degree?

OPT is only for a higher degree than your last degree. As you already received pre-completion OPT for your PhD degree, MS doesn’t qualify as a higher degree.

However, if they consider only the degrees you have actually received, you will qualify. I suggest talking to an attorney as your scneario is an unusual one.