UPDATE 2-Uralchem buys 20 pct stake in Russia's Uralkali

* Follows sale of Kerimov's 21.75 pct stake (Releads, adds analyst quotes, share reaction)

from Reuters: Hot Stocks http://feeds.reuters.com/~r/reuters/hotStocksNews/~3/FrF8C4I0kTw/story01.htm