BUZZ-S.Africa-exposed stocks under pressure after S&P downgrade
** Shares (Berlin: DI6.BE - news) in companies with exposure to South Africa slip after S&P downgrade led to rand weakness
** Investec (-3.2%), Steinhoff (-2%) and Old Mutual (Other OTC: ODMUF - news) (-2.8%) at the bottom of Stoxx 600; Mediclinic among top fallers
** Investec (LSE: INVP.L - news) and Old Mutual shares have fallen 11-13 pct since President Jacob Zuma sacked respected Finance Minister Pravin Gordhan on Thursday
** South Africa's rand fell sharply on Tuesday, extending its losing streak into a seventh straight session after S&P cut South Africa's credit rating to junk status on Monday
** More weakness ahead: Analysts say increased likelihood of credit downgrades by Moody's and Fitch is set to put pressure on the rand this week (Reuters Messaging: thyagaraju.adinarayan.tr.com@reuters.net; Twitter (Swiss: TWTR-USD.SW - news) @thyagu)