Complex sentence: It was formatted as a country music station until 1977, when it was sold to Troy businessman R.E. Shelley and became Top-40 "WRES", the new call letters being Shelley's initials.
Split into simpler sentences: It was formatted as a country music station until 1977. In that year, the station was sold to Troy businessman R.E. Shelley and became Top-40 "WRES", the new call letters being Mr. Shelley's initials.