Divinyl benzene and/or diisopropenyl benzene in hydrocarbon solvent is added over a period of time at low temperature to a hydrocarbon solvent containing a C.sub.2-20 normal, secondary or tertiary alkyl or cycloalkyl lithium compound and a tertiary alkylamine having 2-4 carbon atoms prepared at low temperature to provide an initiator having an average of from 4 to 9 C-Li sites and a VPO Mn of from about 750 to 4,000. These initiators are useful in polymerizing dienes and vinyl monomers to provide star polymers having an average of from about 4 to 9 arms or branches. These star polymers among other things are useful low profile or low shrink additives for FRPs, e.g., glass fiber reinforced plastics.