Negative balance on wallet

hi, sorry if i made the post in wrong topic. i've seen some bitcoin address's on blockchain.info airpone.com and that has negative balance like -1.2 btc or -0.05
how it work's like this?

for example :
https://apirone.com/btc/address/1GqcMJn3xsJ1yboigQ4gbHopN4EMTYDrsK