Would the addition of bond or equity funds make M2 a better indicator of nominal GDP?

John Duca assesses the possibility that adding bond mutual funds, equity mutual funds, or both to M2 would improve this monetary aggregate's ability to forecast nominal GDP growth. He finds that M2B (M2 plus bond funds) and M2+ (M2 plus bond and stock funds) are statistically significant in explaining past nominal GDP growth. Duca further shows that M2B and M2+ each yield better forecasts of nominal GDP growth since 1990 than does M2, but to a lesser extent when the federal funds rate and the ten-year Treasury note yield are included in his forecasting model. Because bond and equity mutual funds are less directly influenced by the Federal Reserve than M2, Duca cautions that, relative to M2, M2B and M2+ are likely to be less controllable by the Federal Reserve. ; Given these findings, Duca argues that M2B and M2+ show promise as information variables that the Federal Reserve may use along with other economic indicators in setting monetary policy. Recent forecast results and anecdotal information suggest that if equity funds continue to become more substitutable for nontransactions deposits, M2+ may prove to be increasingly helpful in this capacity.