Yes, some arenas within Economics are considered STEM degrees according to the most recent list of STEM programs.
The following are the STEM Designated Degree Programs available in the field of economics:
- Econometrics and Quantitative Economics
- Pharmacoeconomics/Pharmaceutical Economics
That is according to the U.S. government. More broadly, economics would generally fall under STEM because it heavily involves both science and mathematics.
Source: ICE.gov (most recent list found as of June 2018)