N.Y. Comp. Codes R. & Regs. tit. 3, § 410.11
(d) such other assets as approved by the superintendent upon written application. In determining whether to approve such other assets, the superintendent shall ascertain the following as applicable:
(2) if bonds, whether the bonds have an investment grade rating from either Moody's Investors Services, Inc., Standard & Poor's Corporation or Fitch Investors' Service, Inc.
If the superintendent determines than an asset which otherwise qualifies under subdivisions (a) through (c) of this section shall be valued for purposes of this Part at less than the amount otherwise required by this Part, the superintendent shall so notify the licensee which shall thereafter value such asset for purposes of this Part as directed by the superintendent.
In addition to the assets described in sections 591(4) and 591-a(3) of the Banking Law, the following assets are eligible for deposit for purposes of section 410.10 of this Part: