Algorithmic trading and passive indexing create boom-bust cycles where rapid gains are followed by hard technical and fundamental ceilings that halt momentum.

"Modern markets are dominated by automated quantitative models, target-date funds, and passive indexing flows. When a macro green light hits the tape, algorithmic buying hits all 500 stocks simultaneously, driving the index straight up in a compressed window. However, once that initial flood of cash is deployed, the index hits a hard fundamental and/or technical ceiling."