The report uses a methodological approach developed by W. S. Jevons and A. L. Chizhevsky. Solar cycle years were numbered according to the order established in solar astrophysics, grouped, and compared with the arithmetic mean values of the geomagnetic index Ap and the effective US federal funds rate with a lag of 1 year. The results showed that the Fed's interest rate with a 1-year lag is minimal in years of extreme values (maximums and minimums) of the geomagnetic index Ap. During periods of maximum values of the geomagnetic index Ap, suppressed melatonin synthesis and the accompanying serotonin deficiency lead to increased pessimism. During periods of minimum values of the geomagnetic index Ap, which are characterized by a low ultraviolet index, insufficient serotonin synthesis and increased pessimism are observed. In both cases, collective pessimism triggers a slowdown in business activity, forcing the Federal Reserve to lower interest rates to stimulate the economy. The coefficient of determination in the diagram average geomagnetic activity coefficient Ap - average Fed interest rate with a one-year lag is 0.9733. This means that the current year's Ap coefficient can be used to determine the forecast value of the Fed interest rate next year. The forecast value of the Fed interest rate for 2026 is 3.75%, and for 2027, 3.3%. The study also found a strong correlation between the geomagnetic Ap index and annual US GDP growth rates over the period 1954–2025. Annual US GDP growth rates decline significantly at extremes of the geomagnetic Ap index, prompting the Federal Reserve to lower the Fed rate with a lag of approximately one year. The projected annual US GDP growth rate for 2026 is 2.6%.
Белкин Владимир Алексеевич (Wed,) studied this question.