Clampett's fortune continues to soar alongside the price of oil. Milton Drysdale, new CFO, former family banker, struggling to bring company management up to international standards. Some successes: Jed no longer quoted in annual report as being "happier than a cat at a fish fry" about stock price; shotguns, rifles banned from executive suites. Room for improvement: Saudi Aramco delegation reportedly offended after being served lunch of "possum-fried critter" by provocatively attired Ellie May; one Harvard-trained management consultant dismissed as "green enough to stick in the ground and grow." Jed increasingly devoted to philanthropic endeavors, recently endowed "Cousins Consanguinity Center" outside of Tahlequah, Okla. Member since 1962.

http://www.forbes.com/2007/12/11/fictional-characters-wealth-oped-books-fict1507-cx_de_mn_1211fictionalintro.html

I just saw an episode where Miss Hathaway states Jed's wealth at 34 million. This was early on in the series, so I'm sure it doubled or better after that. Huge money for the 60s.

Jed's millions must have been invested very well, as the stated amount kept growing steadily through the series. It started at 25 million, then a few years later it was 34 million. It kept going up and in the last season I think it was around 85 or 90 million.