BUZZ-Mining cos: plumbing new depths

** Anglo American (LSE: AAL.L - news) & BHP Billiton top fallers on a 0.5 pct firmer FTSE 100 index, both down c.3 pct, as Credit Suisse (LSE: 0QP5.L - news) cuts ratings on pair amid dramatic price falls in their key commodities

** CS reckons iron ore only part way through a protracted multi-yr downturn due to weak demand (Chinese property) & robust low cost supply

** Notes sector has more than halved in its market weighting since 2010 & is no longer a 'need to own'

** Broker downgrades BHP to "underperform" vs "neutral"; says valuation expensive at c.30x spot PE with market pricing in a recovery in oil prices to over $70/b & capex will need to be cut further, increasingly at the expense of future growth

** CS cuts Anglo to "neutral" vs "outperform"; says balance sheet concerns will persist until assets are sold

** Investec (LSE: INVP.L - news) also bearish on sector, citing increased price volatility & weakening Chinese demand: downgrades BHP to "sell" vs "hold", Anglo American & Rio Tinto to "hold" vs "buy"

** Stoxx 600 basic resources index down 1.7 pct (RM (LSE: RM.L - news) : tricia.wright1.thomsonreuters.com@reuters.net; RM: alasdair.pal.thomsonreuters.com@reuters.net)