Large-Load Tariff Decisions and Utility Market Responses

U.S. regulators are adopting large-load tariffs to allocate the financial risk created when utilities build long-lived infrastructure for data centers and other concentrated loads. This paper studies 15 regulator-verified, exact-dated first final tariff decisions covering 13 listed utility parents and 13 states from 2022 through 2026. Customer-specific special-contract approvals are excluded from the primary sample.

Expected returns are estimated over trading days [-120,-21]; the primary event window is [-1,+1]. Repeated decisions are collapsed to listed-parent means for exact sign-flip inference. The mean SPY-model cumulative abnormal return is 0.39 percentage points (p = 0.353; bootstrap 95 percent interval:-0.40 to 1.14), providing no evidence of average repricing under the primary model.

The XLUadjusted [-1,+1] estimate is positive, but alternative timing windows and influence checks weaken it, making the valuation conclusion benchmark-, window-, and influence-sensitive. A transparent mean-adjusted log-volume measure rises by 0.150 log points, or approximately 16.2 percent. The parent-level result is positive (p = 0.028) but does not survive event-date aggregation (p = 0.110).

The log post/pre realized-risk ratio is not distinguishable from zero. The evidence is consistent with, but does not establish, a dependence-sensitive attention response; valuation conclusions are not robust across specifications. The design cannot identify project-level incidence or downstream ratepayer effects.