Here are some novel ones:

“...to be a successful trader, I must love to lose money and hate to make
money...The first loss is the best loss; there is no better loss than the first
loss…Trading is a discipline.”
From EEK, (memoirs of CBOT member Everett Klipp (1995)).

“One of the critical criteria I use in judging my traders is their ability to take a
loss. If they can’t take a loss, they can’t trade.”
John Mack, Morgan Stanley CEO, in a 1991 deposition.

“If you have bad inventory, mark it down and sell it quickly.”
Attributed to Bear Stearns Chairman Alan “Ace” Greenburg, describing
his penchant for quickly selling losing trades, in the Wall Street Journal (“If Wall Street were Olympian, He’d Ace the Marathon,” March 8, 1999).

“...so, as our discipline requires, we sold.”
J. Stowers, CEO, American Century Funds, in a 12/10/97 letter to investors.

“Never meet a margin call. (In other words, if the market is going against you,
concede defeat quickly and liquidate before you really lose your shirt.)”
James Grant, editor, Grant’s Interest Rate Observer, quoted in
BusinessWeek (“Failed Wizards of Wall Street,” September 21, 1998).