Entry in progress—B.P.
 
Investopedia
What Does Yellow Knight Mean?
A company that was once making a takeover attempt but ends up discussing a merger with the target company.
 
The Free Dictionary
Yellow Knight
A company that offered a hostile takeover but has since changed its mind and decided to discuss a merger. A yellow knight’s management may decide that a hostile takeover would be too expensive or otherwise difficult but still believes that the target company would be advantageous. The term is derogatory and implies that the acquiring company (who would have been a black knight) has cold feet or has gone “yellow.” One would expect the term to be used by the board, management, or even employees, rather than shareholders.
     
Google Books
Business Week
Issues 2695-2703
1981
Pg. 85: 
“Yellow knight” is a term that some on Wall Street are applying to both Conoco Inc. and Cities Service Co.
   
Wisdom Wise
Friday, February 05, 2010
Knights
In the corporate world, we have many kinds of knights.
White Knight, Black Knight, Gray Knight and Yellow Knight
(...)
A Yellow Knight is a company that attempts a hostile bid to a takeover but chickens out at the eleven hour and ends up with a friendly merger discussion instead.
Posted by Ben Gan at 10:16 AM
 
KnowledgeOman.com
Surumi Sageer
07-08-2010, 10:08 AM
Yellow Knight
Yea,there are quite a bit of “knights” in business context.😊
The Yellow Knight is a company which starts off my making an offer to take over another company but ends up discussing about merging both of them.