KANSAS CITY, Mo. (AP) — Jim Stowers Jr., the billionaire founder of one of the nation’s leading investment management firms who gave away most of his fortune to fight disease, has died. He was 90.

The Kansas City, Mo., philanthropist, whose tenacity in business was just as fierce as in his fight for stem-cell research, died Monday after a period of declining health, according to a news release issued by his namesake research firm and the investment firm he founded, American Century Investments.