Gray Knight (Grey Knight)

Entry in progress—B.P.
   
Wikipedia: White knight (business)
In business, a white knight, or “friendly investor” may be a corporation, or a person that intends to help another firm. There are many types of white knights. Alternatively, a grey knight is an acquiring company that enters a bid for a hostile takeover in addition to the target firm and first bidder, perceived as more favorable than the black knight (unfriendly bidder), but less favorable than the white knight (friendly bidder).
 
The first type, the white knight, refers to the friendly acquirer of a target firm in a hostile takeover attempt by another firm. The intention of the acquisition is to circumvent the takeover of the object of interest by a third, unfriendly entity, which is perceived to be less favorable. The knight might defeat the undesirable entity by offering a higher and more enticing bid, or strike a favorable deal with the management of the object of acquisition.
 
The second type refers to the acquirer of a struggling firm that may not necessarily be under threat by a hostile firm. The financial standing of the struggling firm could prevent any other entity being interested in an acquisition. The firm may already have huge debts to pay to its creditors, or worse, may already be bankrupt. In such a case, the knight, under huge risk, acquires the firm that is in crisis. After acquisition, the knight then rebuilds the firm, or integrates it into itself.
 
Investopedia
What Does Gray Knight Mean?
A second, unsolicited bidder in a corporate takeover. A gray knight enters the scene in order to take advantage of any problems between the first bidder and the target company.
 
The Free Dictionary
Gray knight
In a merger or acquisitions, a gray knight is an acquiring company that outbids a white knight in pursuit of its own best interests, although it is friendlier than a hostile bidder.
 
Google Books
Takeovers & Freezeouts
By Martin Lipton and Erica H. Steinberger
New York, NY: Law Journal Seminars Press
1978 (date of original publication; there have been several updates and Google Books has a 2003 edition—ed.)
Pg. 6-178:
Confidentiality Agreements. In the search for a White Knight or White Squire, it is advisable to obtain an agreement that the prospective White Knight will treat any information about the target confidentially and will not become a Grey Knight or Black Knight by buying shares in the market or making a tender for the target without the target’s approval.
 
Google News Archive
10 February 1984, Lakeland (FL) Ledger, “The taking of America” by Art Buchwald, pg. 6C, col. 1:
“It sounds expensive.”
“You better believe it. Now if you can’t find a White Knight, you look for a ‘Gray Knight.’ A Gray Knight is someone the Target isn’t in love with, but could sleep with if she had no other choice.”
“What about the Black Knight?”
“The Black Knight is a third party that comes into the bedroom uninvited at the last moment to spoil the wedding night by tendering a higher offer.”
 
22 June 1986, New York (NY) Times, “Invasion of the Arbs” by William Safire, pg. SM6:
Readers of this space bought at the low such phrases as poison pill (a device to make takeovers more difficult) and white knight (a friendly suitor who will guarantee nervous management platinum parachutes); the the past decade, other Wall Street nonce phrases have withered, such as gray knight (an opportunistic second bidder),...