SHANGHAI B shares rose yesterday on anticipation the United States was preparing to renew China's Most Favoured Nation (MFN) trading status. Trading was thin, however, with attention focused on stocks that have strong export sales and on the three companies that have American depositary receipts (ADRs). ''Good news on the MFN front helps ADR stocks in particular, since these are tailored for American investors,'' a Shanghai floor trader said. The Credit Lyonnais B-share index closed up 17.42 points, or 2.26 per cent, at 786.98 on total turnover of US$4.63 million, down from $8.36 million on Tuesday. Bloomberg reported that 19 stocks closed up, five down and four were unchanged. The A-share index was down 24.97 points, or 0.78 per cent, to close at 3,192.96. Radial-tyre manufacturer Tire and Rubber was among the most active issues for the third successive day, closing unchanged at 58 US cents, with 882,000 shares traded. ''We are recommending this stock at current levels and are forecasting 15 per cent net profit growth for 1994,'' said Newman Mou, a trader with Smith New Court. Yaohua Pilkington Glass also was active, rising 1.2 per cent to $1.022 with 929,700 shares changing hands. Brokers said thin trading levels remained a problem since the bigger China funds found it hard to buy enough shares to make the effort worthwhile.