Subsequent to oxidation of glyceraldehyde 3-phosphate by NAD+ to form 1,3 biphosphoglycerate (BPG), is the formation of two molecules of 3-phosphoglycerate and two molecules of ATP. What's going on? Aside from the NADH produced earlier, which is not of bioenergetic purpose in the anaerobic context, the steps of glycolysis have been devoted to producing BPG. The formation of 3-phosphoglycerate and ATP from 1,3 biphosphoglycerate (1-3-BPG) and ADP is spontaneous because the phosphate bonds of 1,3-biphosphoglycerate hold even more free energy than those of ATP.