What happens to the black stallion in the end?
He races against the best racehorses of that time, Sun raider and Cyclone. This is the first book of the series.
In the book series The Black is taken back to Arabia to be the racehorse of Abu Kub Ja Ben Ishak but when Ben Ishak dies he bequeaths The Black to Alec Ramsey and he is brought back to the USA to live with Alec. He then becomes the head Stud of Alecs Racing Stud and has sons and daughters that are champions. he lives out his life with Alec, having many adventures and in the last book they are still together as far as i know.