Or when the shares of Books-A-Million, a retailer, rose tenfold within three days on the back of an upgrade to its existing website.

ECONOMIST: Michael Lewis

The Warped Tour website powered by Vixlet will completely upgrade the user experience from a flat web experience to one in which fans will be able to stay connected year round, and continue to bond over their favorite bands and tour experiences.

FORBES: Introducing Vixlet

It said customers were alerted to the upgrade by letter or on the website and the new system would offer additional benefits to these customers.

BBC: Anger over Abbey's online glitch

Once you have booked a ticket on the El Al's website, a pop-up message tells you if an upgrade auction is available.

WSJ: El Al, Virgin Atlantic Are Airlines That Auction Upgrades to Business Class