There are two kinds of traders who have been called “pajama” (or “pyjama”) traders. A “pajama trader” is a small investor, who might trade from home (while wearing pajamas). “China’s stock market and the rise of the ‘pyjama traders’” was a story on BBC News published on January 13, 2016.
 
In the United States, a “pajama trader” is often someone who trades in the pre-market, such as between midnight and three am, long before the U.S. markets officially open. A “pajama trader” is a “day trader” who trades at night.
   
“Pajama trader” was cited on Twitter on March 12, 2010. The term became popular in 2015 and 2016.
 
   
Investopedia
What is the ‘Pre-Market’
The pre-market is the period of trading activity that occurs before the regular market session. The pre-market trading session typically occurs between 8:00 - 9:30 A.M. EST each trading day. Many investors and traders watch the pre-market trading activity to judge the strength and direction of the market in anticipation for the regular trading session.
   
Twitter
Trader Bob
‏@StockBrain99
But if you want to make money become a pajama trader like Trader Bob http://www.einsteinstocktraders.com
2:03 PM - 12 Mar 2010
 
Twitter
Trader Bob
‏@StockBrain99
Pajama Trading http://www.short-term-stocktrading.com/pajama_trading.htm
6:48 AM - 16 Apr 2010
 
Twitter
daniel-san
‏@danandreas
@fuinhaz, shorts don’t make mkt go down. neither do pajama traders. market takes wool from whatever side has most sheep.
7:42 PM - 24 Aug 2010
 
Twitter
CFD & Spread Bet
‏@CFDandSpreadBet
New blog post - Is your daily trading preparation up to scratch? – The unwelcome rise of the pyjama trader! - http://ow.ly/kqkD8
11:42 AM - 25 Apr 2013
 
Twitter
CFD & Spread Bet
‏@CFDandSpreadBet
Are you one of the growing army of pyjama traders? - http://ow.ly/lryo7
4:50 AM - 28 May 2013
 
Twitter
Vix Voss
‏@iceman_cry
If u just realized 95% of all loser piker pajama traders rely on analysis that is no better than coin flip, you are probably among them.
1:26 PM - 16 Mar 2014
   
CBNC.com
Don’t fear futures—just a few guys in PJs: Cramer
Matthew J. Belvedere | @Matt_Belvedere
Tuesday, 1 Sep 2015 | 10:01 AM ET
(...)
In his latest knock on the importance of the premarket, Cramer said in a “Squawk on the Street” rant: “Stop fearing the futures. There’s probably like, I don’t know maybe, 10 guys in a room in their pajamas at 4-o’clock this morning.”
 
Always an earlier riser himself, Cramer railed: “I was up this morning at 3:30 looking at the futures. I said, ‘Oh my, there’s someone in their pajamas right now, selling them down.’”
 
Twitter
Jason Norine
‏@JGN74
@jimcramer   but but but the pajama traders must know something…oh, maybe they don’t. “these guys love to lose money”
Classic Cramer
8:21 AM - 15 Sep 2015
   
BBC News
China’s stock market and the rise of the ‘pyjama traders’
By Vincent Ni
13 January 2016
Share
China’s volatile shares have affected millions of individuals - the shop owners, pensioners and other small traders, who make up 80% of China’s investors. How have China’s stock exchanges come to be dominated by “traders in pyjamas”?
 
Twitter
Jim Cramer
‏@jimcramer Jim Cramer Retweeted Nick Walker
That’s why I call them the Pajama traders. They are clueless people who sit around in their pajamas and do no work Jim Cramer added,
Nick Walker @nw3
@ReformedBroker there’s a disconnect between the opinion of pajama futures traders and the business hour traders. (@jimcramer)
2:30 PM - 18 Jan 2016
 
Twitter
Ron Green
‏@ronagre8
@cvpayne @SprtsGamer hi what do they mean , when they say, Pajama trader compared to day traders
3:23 PM - 20 Jan 2016
 
Twitter
Rodney R.
‏@RRBU81
I love it when they call people who trade overnight Pajama traders. $SPY
8:57 AM - 3 Feb 2016
 
Twitter
FF ‏@FatF1nger Feb 29
@megadave5000 no I mean DTF:  Day Time Frame….zero indication OTF is active from where I’m sitting
 
Dr. Shadow
‏@megadave5000
@FatF1nger ok gotcha I was trying to reconcile - was not aware of DTF acronym.  Basically pajama traders?
9:20 AM - 29 Feb 2016
 
Zero Hedge
WTF Chart Of The Day: Without “Pajama Traders”, Stocks Have Gone Nowhere In 11 Years
Submitted by Tyler Durden on 03/28/2016 11:48 -0400
There appears to be two sure-fire ways to make money in these ‘efficient’ markets - Buy before The Fed speaks…
 
or trade ‘em after midnight…
 
To be clear, this means without the gains achieved between midnight ET and 3amET, the S&P 500 futures market since 2005 would have gone nowhere!  - It seems the so-called “pajama traders” may be on to something after all?