From MacKenzie-Childs LLC v. Rowland, 2009 U.S. Dist. LEXIS 71777 (W.D.N.Y. Aug. 14, 2009):

Because corporations may only act through representatives, "any privilege that attaches to communications on corporate matters between corporate employees and corporate counsel belongs to the corporation, not to the individual employee[;] employees generally may not prevent a corporation from [asserting or] waiving the attorney-client privilege arising from such communications." United States v. Int'l Bhd. of Teamsters, 119 F.3d at 215. The power to assert or waive a corporation's attorney-client privilege generally rests with the corporation's management and is exercised by its officers and directors. Commodity Futures Trading Comm'n v. Weintraub, 471 U.S. at 349.

As the Supreme Court has observed,

[W]hen control of a corporation passes to new management, the authority to assert and waive the corporation's attorney-client privilege passes as well. New managers installed as a result of a takeover, merger, loss of confidence by shareholders, or simply normal succession, may waive the attorney-client privilege with respect to communications made by former officers and directors. Displaced managers may not assert the privilege over the wishes of current managers, even as to statements that the former might have made to counsel concerning matters within the scope of their corporate duties.

Id. Where one corporation merely sells its assets to another, however, the privilege does not pass to the acquiring corporation unless (1) the asset transfer was also accompanied by a transfer of control of the business and (2) management of the acquiring corporation continues the business of the selling corporation. See, e.g., Orbit One Commc'ns, Inc. v. Numerex Corp., 255 F.R.D. at 104 ("[i]f the transaction is nothing more than an asset transfer, the successor company does not acquire the former company's privilege[;] [c]onversely, where efforts are made to run the pre-existing business entity and manage its affairs, successor management stands in the shoes of prior management and controls the attorney-client privilege with respect to matters concerning the company's operations") (internal quotations and citations omitted); Soverain Software LLC v. The Gap, Inc., 340 F. Supp. 2d 760, 763 (E.D. Tex. 2004) ("[i]f the practical consequences of the [asset sale] result in the transfer of control of the business and the continuation of the business under new management, the authority to assert or waive the attorney-client privilege will follow as well"); Zenith Elecs. Corp. v. WH-TV Broad Corp., 2003 WL 21911066, *1 (N.D. Ill. 2003) ("the mere transfer of some assets from one corporation to another . . . does not transfer the attorney-client privilege"); In re Grand Jury Subpoenas 89-3 and 89-4, 734 F. Supp. 1207, 1211 n.3 (E.D. Va.) ("[a] transfer of assets, without more, is not sufficient to effect a transfer of the privileges; control of the entity possessing the privileges must also pass for the privileges to pass"), aff'd in relevant part, 902 F.2d 244 (4th Cir. 1990); Sobol v. E.P. Dutton, Inc., 112 F.R.D. 99, 103 (S.D.N.Y. 1986) (attorney-client privilege did not pass to acquiring corporation in asset sale because acquiring corporation was not successor-in-interest to or new management of the selling corporation).

Note that the Soverain excerpt in the last paragraph does not appear to require continuity of management, as suggested in the first sentence of that paragraph.