Nintendo reported on January 30th that LTD shipments for the Wii U console were as follows:
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As of December 31st, 2012:
Japan - 830,000 Wii U units shipped
America - 1,320,000 Wii U units shipped
Europe + Other - 900,000 Wii U units shipped
[B]World - 3,060,000 Wii U units shipped[/B]
Also, Nintendo reported on April 24th that LTD shipments for the Wii U console were as follows:
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As of March 31st, 2013:
Japan - 920,000 Wii U units shipped
America - 1,520,000 Wii U units shipped
Europe + Other - 1,010,000 Wii U units shipped
[B]World - 3,450,000 Wii U units shipped[/B]
So, in the three month period from January to March, the Wii U shipped 390,000 extra Wii U consoles worldwide.
It therefore follows that assuming an identical, flat trend for all of 1H, upon Nintendo's July 31st Q1 earnings release, Wii U worldwide shipments will have hit ~3.84 million units for the quarter ending June 30th, 2013.
The "4 million units sold" figure you've seen is an optimistic projection of LTD Wii U shipments through the end of 1H.
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Optimistic investor projections:
As of June 30th, 2013:
World - 4,000,000 Wii U units shipped
World - 550,000 LTD unit increase in the past three months (compare to a 390,000 LTD unit increase from January through March)
World - 183,333 average monthly increase from April through June
The "5 million by November" claim also operates under the assumption of optimistic projections.