Time to stop buying Severn Trent shares - broker Proactive uses images sourced from ShutterstockIt is time to stop buying Severn Trent PLC (LSE:SVT) shares, that's according to investment bank Jefferies, which has downgraded the water utility to 'Hold' after a roughly 10% share-price rise since January, which analysts claim leaves less room for upside against an increasingly uncertain political and regulatory backdrop. Jefferies estimates regulatory reopeners could add around 5%-10% to sector regulatory asset base growth by 2030. However, "the scope, economics, and funding remain uncertain", particularly for Severn Trent and Pennon. Pennon also remained at Hold, although the target was cut 15% to 500p. Jefferies highlighted operational penalties, below-target regulated returns and a tighter balance sheet, forecasting regulated-business gearing of around 67% during AMP8.