The fnex whitepaper argues for increased portfolio diversification through alternative investments, like hedge funds and private equity, due to the rising correlation between stocks and bonds and the inadequacy of traditional 60/40 portfolios. With the prospect of longer retirements and significant downturns, many investors are turning to alternatives to enhance returns and reduce risks. The document highlights the growing acceptance of alternatives among institutional and retail investors, with a notable increase in allocations since the financial crisis.