Adele sold over 2.3m copies of '25' in the US in the first 3 days

"It’s confirmed. Adele’s 25 has broken the single-week U.S. album sales record, according to Nielsen Music.
After processing the first sales reports from Monday, Nov. 23, the album has already sold at least 2,433,000 in pure album sales in slightly more than three days. That sum beats the single-week record for an album since Nielsen began tracking sales in 1991, set by *NSYNC’s No Strings Attached, when it debuted with 2,416,000 in the week ending March 26, 2000.
Adele's '25' Is the 20th Album to Sell a Million Copies in a Week: See the Full List
Nielsen Music began tracking point-of-sale music purchases in 1991. Prior to 1991, there was no authoritative music sales tracking service in the U.S. and thus, it was mostly unknown how many copies of an album or song/single were sold in a single week.
25 was released on Nov. 20 through XL/Columbia Records. Yesterday (Nov. 23), Nielsen reported that 25 had sold at least 2.3 million copies in its first three days of release (through Nov. 22)."

Source:  Billboard, 24th November 2015
Update - 3.38m in the first week in the US