James D. "Jim" Oberweis (born June 10, 1946), is a businessman and investment manager. He is most notable as a Chicago area owner of the Oberweis Dairy, in North Aurora, founded in 1915 by Peter J. Oberweis. Oberweis campaigned for the Republican nomination for a U.S. Senate seat from Illinois unsuccessfully in 2002 and 2004, and campaigned for the Republican nomination for Governor of Illinois unsuccessfully in 2006. Oberweis was unsuccessful in his March 2008 bid for Illinois' 14th congressional district to succeed Dennis Hastert. He was unsuccessful in his bid for the same seat in November 2008.
Oberweis attended the University of Illinois at Urbana-Champaign where he obtained a bachelor of arts degree and was a member of the Phi Kappa Tau fraternity. He went on to obtain a master's degree in business administration from the University of Chicago. In 1968, he became a junior high school teacher until he changed careers in 1970 to become an investment stockbroker.
Having served on for a major New York Stock Exchange firm, Oberweis founded and published the Oberweis Report newsletter which focused on emerging growth companies. Hulbert Financial Digest ranked the Oberweis Report as one of the top five investment advice newsletters. In 1978, Oberweis and his wife established an investment management company of their own. In 1986, they used their profits to purchase the family business, Oberweis Dairy. A year later, Oberweis founded the Oberweis Emerging Growth Fund which later spawned the Oberweis Micro-Cap Portfolio and the Oberweis Mid-Cap Portfolio. He was also the former owner of Oberweis Securities in Aurora, IL.