concurring in part and concurring in the judgment.
I agree that the judgment of the district court must be reversed. However, in concluding that the defendants violated Rule 10b-5, 17 C.F.R. § 240.10b-5 (1981), I would predicate their duty to disclose the Mid-Allegheny Corporation (MAC) dividend solely on the provisions of Rule 10b-17, 17 C.F.R. § 240.10b-17 (1981), rather than on the complex of theories set forth in Part III-B of Judge Gibbons’ opinion. I thus *944would not reach the question whether the defendants had a duty to disclose under the New York Stock Exchange (NYSE) listing agreement, the Maryland law of fiduciary obligations, or the New York law of contracts.
I.
Rule 10b-17 provides that the failure of an issuer to give ten days’ prior notice of the declaration of a dividend relating to a publicly traded security constitutes a “manipulative or deceptive device or contrivance” within the prohibitions of section 10(b) of the Securities Exchange Act of 1934,15 U.S.C. § 78j(b) (1976).1 Here, it is undisputed that while the common stock of the Baltimore & Ohio Railroad Company was not publicly traded or listed on any national securities exchange (99.63 percent of the common stock was owned by the Chesapeake & Ohio Railway Company), the convertible debentures were publicly traded and were listed on the NYSE. Thus, the B & 0 convertible debentures are a publicly traded class of securities within the meaning of Rule 10b-17.2 It is also undisputed that the B & 0 failed to give ten days’ notice of its action in declaring the MAC stock dividend to the National Association of Securities Dealers (NASD), or to the NYSE in accordance with the procedures set forth in the B & O’s listing agreement with that Exchange.3 Thus, the only remaining question to be answered is whether the declaration of the MAC dividend was an action “relating to” the publicly traded con*945vertible debentures within the meaning of Rule 10b-17. If Rule 10b-17 applies, a duty of disclosure arises, the breach of which provides the predicate for a violation of Rule 10b-5. See generally Chiarella v. United States, 445 U.S. 222, 235, 100 S.Ct. 1108, 1118, 63 L.Ed.2d 348 (1980).4
II.
The defendants argue that the notice requirements of Rule 10b-17 apply only to dividends declared on publicly listed stock. Because the B & O’s common stock was not publicly listed, the defendants argue, no notice was therefore mandated.
In my opinion, this argument contemplates too restrictive a reading of Rule 10b-17. The Rule was meant to protect the ability of investors to exercise their investment rights to the fullest. It does so by operating to ensure that opportunities to exploit benefits associated with security ownership will not be lost by the withholding of material information. As the SEC explained when it proposed Rule 10b-17, in the absence of disclosure of imminent dividend declarations, “purchasers and their brokers may have entered into and settled securities transactions without knowledge of the accrual of such rights and were thus unable to take necessary steps to protect their interests.” Securities Exchange Act Rel. No. 9076, 36 Fed.Reg. 3430 (Feb. 17, 1971).
While it is true that the Rule makes no specific reference to convertible debentures as such, it without question includes such instruments within its classification of “securities publicly traded” and proscribes the failure to give notice of dividends “relating to such class of securities.” See note 2 supra. I agree with the SEC that
[f]or purposes of determining what information is material to security holders, there is a significant difference between the holders of simple debt securities and the holders of debt securities convertible into stock. The latter own contracts to purchase the stock on specified terms and at a specified price and, as a result, have as great an interest in material facts concerning that stock as do the stockholders.
SEC Amicus Brief at 19 n.17.
It is obvious that a stock dividend declared on common stock comes within the terms of Rule 10b-17. It would be anomalous if a stock dividend which becomes payable simply by the exercise of converting a debenture were not considered as “relating to such class of [convertible debenture] securities.” It seems to me that in the context of Rule 10b-17, a dividend “relates to” a security if the declaration of that dividend makes the security significantly more or less valuable, whether by directly increasing or decreasing the value of the security or by enabling the holder of the security to take steps which would either augment the security’s worth or prevent the diminution of its value.
Here, the convertible debentureholders claim that the value of the non-rail assets of the B & O which are represented by the MAC dividend roughly approximates $250 million. Prior to the declaration of the MAC dividend, the debentures included the right to convert to B & O common stock which represented both rail and non-rail assets; after the dividend declaration, the debentures were convertible into B & O common stock which no longer represented the non-rail assets and only represented the rail assets. Tested by the definition set out above, it is evident to me that the declaration of such a dividend in which the convertible debentureholders could share in both categories of assets by exercising their conversion option, is an action which clearly “relates to” this class of securities.
Accordingly, I agree with Judge Gibbons, who has reached a similar conclusion in his opinion where he has indicated that the MAC dividend “related to the convertible debentures since it was material to a decision about exercising the [debentures’] con*946version option.” Op. of Gibbons, J., at 941. Under the analysis I have suggested, the defendants had a duty under Rule 10b-17 to give advance notice to the NASD or the NYSE (and through them to the convertible debentureholders) of the declaration of the MAC dividend. The conceded failure of the defendants to give such notice rendered them liable in damages under Rule 10b-5. That being the case, there is no need to consider whether any other theory is viable which would impose a duty upon the defendants to give notice to the holders of the convertible debentures.
Accordingly, I join Judge Gibbons’ opinion except for Part III-B, and concur in the reversal of the judgment below.
. The Rule states:
(a) It shall constitute a “manipulative or deceptive device or contrivance” as used in section 10(b) of the Act for any issuer of a class of securities publicly traded by the use of any means or instrumentality of interstate commerce or of the mails or of any facility of any national securities exchange to fail to give notice in accordance with paragraph (b) of this section of the following actions relating to such class of securities:
(1) A dividend or other distribution in cash or in kind, except an ordinary interest payment on a debt security, but including a dividend or distribution of any security of the same or another issuer;
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(b) Notice shall be deemed to have been given in accordance with this section only if:
(1) Given to the National Association of Securities Dealers, Inc., no later thán 10 days prior to the record date involved or, in case of a rights subscription or other offering if such 10 days advance notice is not practical, on or before the record date and in no event later than the effective date of the registration statement to which the offering relates. ... [or]
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(3) Given in accordance with procedures of the national securities exchange or exchanges upon which a security of such issuer is registered pursuant to section 12 of the Act which contain requirements substantially comparable to those set forth in paragraph (b)(1) of this section.
17 C.F.R. § 240.10b-17 (1981) (emphasis added).
. Rule 10b-17 is not limited to equity securities. That dividends or other distributions relating to debt securities are covered by the Rule is evident from the Rule’s exclusion from its notice requirement of “ordinary interest payments] on a debt security.” Rule 10b-17(a)(1). This clearly indicates that dividends or other distributions relating to debt securities, other than ordinary interest payments, are governed by the Rule. If Rule 10b-17 covers equity and debt securities, it must cover a mixed debt-equity security such as a convertible debenture.
. The NYSE listing agreement for the debentures, App. at 457a, entered into by the B & O on March 22, 1956, incorporates by reference an earlier listing agreement between the B & O and the NYSE, dated February 18, 1947. That earlier agreement provided:
The Corporation [B & O] will give the Exchange at least ten days’ notice in advance of the closing of the transfer books, or of the taking of a record of its stockholders for any purpose.
The Corporation will publish promptly to the holders of any of its Securities listed on the Exchange any action taken by the Corporation with respect to dividends or to the allotment of rights to subscribe or to any rights or benefits pertaining to the ownership of its securities listed on the Exchange; and shall give prompt notice to the Exchange of any such action; and shall afford the holders of its securities listed on the Exchange a proper period within which to record their interests and to exercise their rights....
Id. at 455a. By its terms, the NYSE listing agreement unquestionably includes any action taken, including the declaration of dividends, which affects convertible debentures.
. Thus, we need not decide whether a violation of Rule 10b-17, like a violation of Rule 10b-5, 17 C.F.R. § 240.1Ob-5 (1981), itself gives rise to an implied right of action for damages under § 10(b) of the Securities Exchange Act of 1934, 15 U.S.C. § 78j(b) (1976).