BUZZ-Tesco's "Finest" store plan bites Marks & Spencer
** Shares in British supermarket and high street chain Marks & Spencer slide 3.7% as rival Tesco plans to go upmarket
** Traders say shares are taking a hit on Tesco's plans to launch a new higher-end store concept with the "Tesco finest" banner
** Marks & Spencer is the second-worst performer on the FTSE 100 index
** Sainsbury's shares also down 1.8% (Reporting by Thyagaraju Adinarayan)