Why Stock prices first began to decline late 1929 because?

Stock prices began to decline in late 1929 primarily due to a combination of speculative excess, overvaluation, and economic instability. Investors, who had heavily speculated on rising prices, started to panic as signs of an economic downturn emerged, leading to widespread selling. The market's volatility was exacerbated by a lack of regulatory oversight and the interconnectedness of financial institutions, which heightened fears about the economy's resilience. This culminated in the Stock Market crash of October 1929, marking the beginning of the Great Depression.