Causal methods ask a harder question than prediction: what would have happened otherwise. In the archive that means event studies around announcements and index changes, difference-in-differences around regulatory shifts, instrumental-variable designs for flow and liquidity effects, Granger-causality and causal-discovery algorithms on multivariate time series, and a growing set of papers that use causal structure to make trading signals more robust to regime change.

What to check when reading. Identification is everything. A credible paper states the counterfactual, explains why the treated and control groups are comparable, shows pre-trends, and reports how the result changes under alternative windows and controls. Granger causality is predictive, not causal, and a paper that treats it otherwise is making a weaker claim than its title. For causal-discovery algorithms on prices, ask whether the discovered graph is stable across sub-periods.