I feel like, to refer to 'billionaires' in the plural, this 'article' should talk about more than Buffett.
Anyway, Buffett's company, Berkshire Hathaway, has a couple different people managing their equities (stock) positions. Buffett certainly could direct some sales or 'dumping,' but most of the activity is carried out by other people than Buffet himself.
That being said, this 'article' is horribly out of date, these position changes were disclosed in the 13F filings for Berkshire Hathaway back in March (so, reflecting a quarter before that, so these moves were technically made back in *2012*.
Lastly, 'he' sells, 'he' (or his company) buys too.
Berkshire has reduced their positions in Johnson & Johnson while taking a huge and much larger position in ExxonMobil. A big position in National Oilwell Varco, energy company SunCo and Dish Network.
You can look up the 13F's for Berkshire every quarter, they're public docuмents.
Berkshire at least isn't 'dumping' stocks.
Maybe some other billionaires are, but you can't prove it, so someone could just as easily say 'they' are swiping up stocks left and right.
Somebody surely is, since the market has been on a tear this last year. An unbelievable tear which shows no signs of abating. This buying sure doesn't appear to be 'retail' investors (regular schmoes) since most anyone with any money still left in their 401k after the last 5-6 disastrous years hasn't jumped back into this market.