BUZZ-Saudi's Yamama Cement tumbles on Q2 earnings

** Shares in Saudi Arabia's Yamama Cement tumble 5.5 percent to 25.60 riyals, lowest level since mid-January ** Company reported 14 percent year-on-year drop in second-quarter net profit to 150.5 million riyals ($40.1 million) ** Also slashed second-quarter dividend to 0.25 riyal per share from 0.75 riyal ** Cited higher fuel prices after government cut subsidies in austerity drive; also depreciation charges on assets, lower sales due to holy month of Ramadan, lower investment profits ** Saudi s