(Adds David Tepper quotes)
NEW YORK, Oct 17 (Reuters) - Billionaire investor Carl Icahn warned on Monday that many S&P 500 companies are "way overvalued," considering soft-to-weakening economic growth in the United States as well as in emerging markets.
Reiterating his stance on equities, Icahn said on CNBC, "I've been concerned for a few years, and more and more concerned. I think it's very difficult when there (are) so many people in the middle class that really don't have the income that they counted on, pension funds are way underfunded ... in a market, economy that has inflation."
Icahn, chairman of Icahn Enterprises, said he is cautious about the U.S. stock market on a long-term basis, but on the short-term period, it is "anybody's guess."
Icahn said he runs a large portfolio and that there are a few gems in the market.
Icahn cited Herbalife Ltd, American International Group Inc and Cheniere Energy Inc as "uniquely undervalued." He added that it takes "years and years and years" to reap huge profits from activism and that serious investors need to be "extremely patient."
About Herbalife, Icahn declined to comment on Bill Ackman, who has been on the opposite side of the bet on the stock, and added that he stood by his major investment.
Herbalife is "undervalued, a good model and gives jobs to a lot of people," Icahn said.
David Tepper, Appaloosa Management president and founder, was on the same CNBC segment and also provided a gloomy backdrop for U.S. equities: "It's a difficult environment. It's an environment (with) OK, not great returns."
Tepper said he is "pretty cautious" on the market and "not outright bearish."
"We're pretty light on the stock market right now. And we have a lot of cash. We're probably more positioned in the bond market right now," he said.
On U.S. presidential candidates Hillary Clinton and Donald Trump, Tepper said: "You have one person with a questionable judgment and the other person that may be demented, narcissistic and a scumbag. I'm not saying which one is which. You can make your own decision on that."
Tepper said, "As far as support, I am sitting on the sidelines. I'll probably vote for one - I'll vote at the end of the day. I'm in Florida, so my vote counts." (Reporting By Jennifer Ablan; Editing by Nick Zieminski and Meredith Mazzilli)