12 C.F.R. § 324.405
(2) Provisions applicable to undercapitalized, significantly undercapitalized, and critically undercapitalized FDIC-supervised institution. Immediately upon receiving notice or being deemed to have notice, as provided in § 324.402, that the FDIC-supervised institution is undercapitalized, significantly undercapitalized, or critically undercapitalized, it shall become subject to the provisions of section 38 of the FDI Act:
(4) Additional provisions applicable to critically undercapitalized institutions.
(i) In addition to the provisions of section 38 of the FDI Act described in paragraphs (a)(2) and (a)(3) of this section, immediately upon receiving notice or being deemed to have notice, as provided in § 324.402, that the insured depository institution is critically undercapitalized, the institution is prohibited from doing any of the following without the FDIC's prior written approval:
(b) Discretionary supervisory actions. In taking any action under section 38 of the FDI Act that is within the FDIC's discretion to take in connection with: