There are a lot of positions that will say applied math or engineering or related quantitative discipline or something like that. I'm not sure the degree is such a big issue, although, personally, I would much rather have an engineering degree, if you ask me. What you should worry about is developing a skill set that they will want, even including non-technical skills. If you don't have the skill set, you could end up like me with my topology PhD, not knowing where you fit in. So, I'd start looking at applied math postings now to see what they want and by the time you get a PhD, you could make yourself very marketable.
I didn't really start this process until the end of my PhD, in addition to not getting internships, which wasn't a very marketable degree to begin with, so I'm now having to develop marketable skills under the pressure of being extremely underemployed and having to do a very difficult job search in the mean time, just in case someone out there is willing to hire me as is. The thing is, it's not just out of ignorance that I wasn't prepared. A big part of why I wasn't prepared is that the PhD was very difficult and took all my energy. Granted, if I had known I was headed out of academia, I would have had plenty of time to do things that industry would like, instead of all the things I was doing to prepare myself for academia.