For decades, investors have relied on a 60/40 portfolio — a mix of 60% stocks and 40% bonds — for steady growth and income. But rising stagflation risks are raising the possibility of a “lost decade” of returns for investors in these balanced portfolios while changing the playbook for portfolio construction, according to Christian Mueller-Glissmann, head of asset allocation research in Goldman Sachs Research, and Maria Vassalou, a co-chief investment officer of Multi-Asset Solutions in the Asset Management Division, in the latest episode of Exchanges at Goldman Sachs.