A “wolf pack” is a loose association of hedge funds (and possibly some other activists) that stop just short of forming a “group” (which would require disclosure under Section 13(d)(3) of the Williams Act once the “group” collectively held 5% or more of any class of the stock of the engaged firm). The essence of the “wolf pack” is conscious parallelism without any agreement to act in concert. The market can quickly recognize a “wolf pack” once its leader crosses the 5% threshold and files its Schedule 13D, and the market responds more enthusiastically to a “wolf pack” than to other activist investors, running up on average 14% in abnormal returns on the date of its public appearance. Also, the “wolf pack” acquires substantially more—at least 13.4% in on recent study. But this may understate, as researchers cannot know how many allies the wolf pack leader has. In the Sotheby’s proxy litigation last year, the CEO of a prominent proxy solicitor, testifying as an expert witness, estimated that hedge funds then held over 32% of Sotheby’s (a mid-cap sized firm).This is a near control block.
The key advantage of joining a “wolf pack” is that it offers near riskless profit. The hedge fund leading the pack can tip its allies of its intent to initiate an activist campaign because it is breaching no fiduciary duty in doing so (and is rather helping its own cause); thus, insider trading rules do not prohibit tipping material information in this context. If one can legally exploit material, non-public information, riskless profits are obtainable, and riskless profits will draw a crowd on Wall Street.
 For a fuller review of these tactics and the legal and market developments that made the “wolf pack” possible, as well as the concept of “group,” see John C. Coffee, Jr. and Darius Palia, “The Impact of Hedge Fund Activism: Evidence and Implications” (available at http://ssrn.com/abstract=2496518)(Oct. 2014).
 See Becht, Franks, Grant and Wagner, supra note 1, at 32. [Full cite: Marco Becht, Julian Franks, Jeremy Grant and Hammes F. Wagner, The Returns to Hedge Fund Activism: An International Study, (available at http://ssrn.com/abstract=2376271)(March 25, 2015).]
 Daniel Burch, CEO of Mackenzie Partners, so testified in the Sotheby’s litigation that hedge funds then held an estimated 32.68% of Sotheby’s. On the basis of the “threat” this constituted, the Chancery Court upheld a special “discriminatory” version of the poison pill. Third Point, LLC, the lead activist, held only 9.62% of Sotheby’s, thus showing the size of the allies that the “wolf pack” leader can assemble. See Third Point, LLC. v. Ruprecht, 2014 Del. Ch. LEXIS 64 (May 2, 2014).
It seems to me that there are several ways of responding to the wolf pack phenomenon.
First, amend Exchange Section 13(d) and the rules thereunder so that conscious parallelism requires filing a Schedule 13D. There is evidence that "wolf pack activity appears to be ostensibly uncoordinated—i.e., no formal coalition is formed—a fact that is usually attributed to an attempt by the funds to circumvent the requirement for group filing under Regulation 13D when governance activities are coalitional." Instead of requiring the SEC and/or the target to undertake the difficult task of proving that ostensibly uncoordinated activity is in fact coordinated, we should amend Section 13(d) to force wolf packs to disclose. After all, isn't sunlight the best disinfectant? In addition, as Wachtell Lipton has been urging for a long time, the 10 day window for filing Schedule 13Ds should be shortened to 2 business days.
Second, courts should be more receptive to arguments that wolf packs constitute a group that "may be liable under Section 16(b) if, in the aggregate, the group’s holdings exceed ten percent of the company’s nonexempt, registered equity securities."
Third, and perhaps most important, the Delaware courts should validate wolf pack poison pills:
... a traditional poison pill follows the federal securities laws in determining when shareholders are considered a “group” and would generally aggregate their ownership if, and only if, they entered into an agreement to act in concert with respect to their stock in the company. There is no definitive legal authority on whether a poison pill would be legally valid if it aggregated stock ownership of investors who patterned their behavior after one another, but did not have an agreement to act in concert. To avoid potential litigation, companies generally utilize the 13D definition of “group” in their shareholder rights plans although this means that their poison pill may not be an effective weapon against a wolf pack.
The Sotheby’s case may cause practitioners to rethink the desirability of adopting a wolf pack pill. Sotheby’s found that the acquisition of stock by members of a wolf pack could be a threat to the corporation based on a pattern of behavior the court described as “conscious parallelism.” The same analysis may also justify a wolf pack clause in a poison pill.