The Rockies added four prospects -- outfielder Yonathan Daza, left-hander Sam Howard, catcher Chris Rabago and right-hander Jesus Tinoco -- to their 40-man roster on Monday to protect them from being exposed in next month's Rule 5 Draft.
Clubs had until 6 p.m. MT to protect eligible players.
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The Rockies now have 37 players on their 40-man roster, leaving them flexibility in case they want to select a player in the Rule 5 Draft, which will take place Dec. 14 at the Winter Meetings in Lake Buena Vista, Fla.
Howard, who was selected in the third round of the 2014 Draft, was the Rockies' No. 12 prospect, according to MLBPipeline.com. The 24-year-old was a combined 5-8 with a 3.32 ERA in 24 games (23 starts) for Triple-A Albuquerque and Double-A Hartford.
Daza, who recently wrapped up an impressive stint in the Arizona Fall League, slashed .341/.376/.466 and stole 31 bases last year for Class A Advanced Lancaster.
Rabago, who was selected in the 13th round of the 2014 Draft out of UC Irvine, threw out 36 percent of attempted stolen bases last season for Lancaster while hitting .272 with a .350 on-base percentage.
Tinoco was acquired by the Rockies from the Blue Jays as part of the Troy Tulowitzki trade. Last season, he was 11-4 with a 4.67 ERA in 24 starts for Lancaster.