FM was the brand of F. Maia Lda, a company based in Barrô, near Agueda, 80km south of Porto, Portugal. In addition to the FM brand the company used the model names FMAIAL and Ranger. It held trademarks for the word 'Ranger' and, weirdly, the letters 'TVT'. TVT was a legendary French manufacturer of early carbon frames - so I can't quite tell what was going on here.

The company was possibly formed in 1981 and was finally liquidated in 2011.

This is not much information, but it is something!