Amazon Prime Day kicks off today: online spending is expected to reach $26.3 billion, retail competition is heating up.

According to the Zhichong Finance APP, the 12th annual Prime Day promotion hosted by Amazon (AMZN.US) officially kicked off on Tuesday local time. This four-day shopping extravaganza will run from June 23 to 26, earlier than the usual July schedule. Amazon stated that the timing adjustment is due to major events such as the World Cup and the 250th anniversary celebration of American Independence happening this summer.