The group explained that, as a result, the rates in effect since April 1, 2025 will remain applicable for the tariff period beginning April 1, 2026, with the exception of the fee for assistance to disabled persons and persons with reduced mobility, whose 15% increase was validated by the ART in its decision of December 16 last year.

As a reminder, on December 17 last year, ART had already refused to approve the rates, causing ADP shares to plunge 12.27% during the December 18 trading session.

According to analysts at Jefferies, the impact on 2026 is negligible, as the rejection simply results in the extension of the 2025 rates. However, the repeated refusals by the regulator further heighten the uncertainty weighing on ADP shares, notes the American investment bank.

Jefferies points out that ART continues to challenge the WACC (weighted average cost of capital, with ART 50 basis points lower), the cost allocation, and the forecasting assumptions, which, according to the regulator, lead to an underestimation of ROCE (return on capital employed) by around 100 basis points.

Jefferies' recommendation on ADP stock remains to hold, with a price target of 122 euros.