12 CFR § 615.5240 - Regulatory capital requirements.
(a) The capitalization bylaws shall enable the institution to meet the capital adequacy standards established under subpart H of this part, part 628 of this chapter, and the capital requirements established by the board of directors of the System institution.
(b) In order to qualify as permanent capital, equities issued under the bylaws must meet the following requirements:
(1) Retirement must be solely at the discretion of the board of directors and not upon a date certain (other than the original maturity date of preferred stock) or upon the happening of any event, such as repayment of the loan, and not pursuant to any automatic retirement or revolvement plan;
(2) Retirement must be at not more than book value;
(3) The institution must have made the disclosures required by this subpart;
(4) For common stock and participation certificates, dividends must be noncumulative and payable only at the discretion of the board; and
(5) For cumulative preferred stock, the board of directors must have discretion to defer payment of dividends.