LAUSR

Abstract Siblings are important sources of support. Male siblings, in particular, are valuable extended family resources in patriarchal societies such as China. This paper examines the effects of the number of brothers on household stock market participation in China. We find that having more brothers increases both the probability of stock market participation and the portfolio share in stocks. This positive effect is more pronounced for individuals who face high income risk, suffer from poor health, lack private insurance, and reside in areas with low financial development and high gender discrimination. In addition, the brother effect persists in recent periods. This evidence highlights the importance of informal risk-sharing networks in household investment decisions. Our results imply that demographic changes such as fertility decline might have unnoticed but sizable impacts on household portfolio choice, especially in countries with strong family ties.