AR

From HelpWiki

'AR' stands for Allowence Races, which is the fifth possible grade for a horse on White Oak Stables Racing. There are, in total, nine different grades for a racehorse. These are: Time Trials, Starter Races, Starter Allowence Races, Allowence Races, GIII, GII, GI and International. Also there is a Maiden grade, which signifies that the horse has not yet raced.

Also, on the news ticker, AR stands for Arabian.