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Standard-error treatment is not visible in the excerpts.",170 "units_stated_in_notes": false,171 "standard_errors_description": "unclear"172 },173 "figures": {174 "uncertainty_shown": "unclear"175 },176 "conclusion": {177 "bounded_claims": true,178 "policy_implications": false,179 "open_questions": true,180 "restates_contribution": true181 },182 "hedging": {183 "level": "moderate",184 "typical_devices": [185 "'consistent with' theory phrasing",186 "'at least in part'",187 "explicit acknowledgment that constraints cannot fully explain the flat SML",188 "listing alternative explanatory factors"189 ]190 },191 "claim_evidence": [192 {193 "claim": "Tighter margin requirements are associated with a flatter SML slope and a higher intercept.",194 "evidence_type": "table",195 "evidence_ref": "Table VI"196 },197 {198 "claim": "The result holds when controlling for additional risk factors and using alternative test assets.",199 "evidence_type": "table",200 "evidence_ref": "Tables VII, VIII"201 },202 {203 "claim": "The borrowing-lending rate spread does not explain the SML slope or weaken the margin effect.",204 "evidence_type": "table",205 "evidence_ref": "Table IX"206 },207 {208 "claim": "Increases in margin requirements reduce margin credit.",209 "evidence_type": "figure",210 "evidence_ref": "Figure 3; Table III"211 },212 {213 "claim": "The SML is flatter in subsamples with higher initial margin requirements.",214 "evidence_type": "figure",215 "evidence_ref": "Figure 1, Figure 4"216 },217 {218 "claim": "Under a common margin constraint, the SML is flatter than in the unconstrained CAPM.",219 "evidence_type": "equation_or_proof",220 "evidence_ref": "Section I eq. (1); Appendix derivation"221 },222 {223 "claim": "The TED spread is a poor proxy because it is endogenous and has the wrong-signed relation in prior work.",224 "evidence_type": "prior_literature",225 "evidence_ref": "Cohen, Polk, Vuolteenaho (2005); Frazzini and Pedersen (2014)"226 }227 ],228 "structural_summary": "The paper opens with the flat-SML anomaly and the leverage-constraint theory that explains it. It then argues that existing proxies such as the TED spread are flawed and proposes the Fed's margin requirement as a direct measure. The theory section summarizes a constrained-CAPM model, with the derivation in the appendix. A long institutional section documents the regulation, what drives its changes, and its effects on margin credit. A two-step SML estimation, following Cohen, Polk and Vuolteenaho, feeds time-series regressions on the margin level. Results are followed by robustness checks, a cost-of-leverage control and a short-sales/disagreement analysis. 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