RYDEX SERIES FDS INVERSE MID CAP MUTUAL FUNDS USMF - What does RYDEX SERIES FDS INVERSE MID CAP MUTUAL FUNDS USMF mean? - What does RYDEX SERIES FDS INVERSE MID CAP MUTUAL FUNDS USMF stand for? - RYDEX SERIES FDS INVERSE MID CAP MUTUAL FUNDS USMF meaning