Final answer:
The Institute of Business Appraisers is the oldest professional organization dedicated to the appraisal of closely held businesses, founded in 1978.
Step-by-step explanation:
The oldest professional organization devoted to the appraisal of closely held businesses is the Institute of Business Appraisers (IBA). The IBA was founded in 1978 and played a pioneering role in the development of business valuation as a profession. Its primary focus is on enhancing the professionalism of business appraisers through education, certification, and the promulgation of ethical and valuation standards.