WASHINGTON, Dec. 1, 2017 /PRNewswire/ — Fannie Mae (OTC Bulletin Board: FNMA) priced its twelfth Multifamily DUS® REMIC in 2017 totaling $1.6 billion under its Fannie Mae Guaranteed Multifamily Structures (Fannie Mae GeMS™) program on November 29, 2017. The M15 transaction included two…