asteroid 2000 EM26, with a diameter of 885 feet, roughly three football fields, has been quite elusive since its discovery. According to broadcast, the asteroid was discovered in 2000 and was observed 32 times but has not been seen since March 14, 2000.
What the article leaves out is that it was first observed on March 5, 2000. So all confirmed observations were within a 9 day range, which is a pretty bad data set to accurately predict an orbit. Apparently several dozen attempts to find it have failed in the last fourteen years.
I'm kind of surprised it wasn't already considered lost.