Why Etherscan is reporting negative token balances?

I am wondering if its possible a holder to have negative balances as reported by Etherscan. Bellow are the links for the cases that I spotted: KICK token holder 0xc12d1c73ee7dc3615ba4e37e4abfdbddfa38907e: https://etherscan.io/token/0xc12d1c73ee7dc3615ba4e37e4abfdbddfa38907e?a=0xc12d1c73ee7dc3615ba4e37e4abfdbddfa38907e#tokenAnalytics WETH token holder 0x76481caa104b5f6bccb540dae4cefaf1c398ebea: https://etherscan.io/token/0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2?a=0x76481caa104b5f6bccb540dae4cefaf1c398ebea#tokenAnalytics How reliable is for applications that keep track of historical ERC20 token balances based on just ERC20’s Transfer events…