The $200 million Bitmart hack was first revealed by Peckshield, a blockchain security and data analytics company, who initially identified a transfer of roughly $100 million over the Ethereum blockchain.
Further investigation from the team revealed a concurrent hack of $96 million over the crypto exchange’s BSC reserves:
Crypto exchange Bitmart lost nearly $200 million in a hot wallet compromise hosted over the Ethereum (ETH) and Binance Smart Chain (BSC) blockchains.

Total estimated loss: ~200M (~100M on @ethereum and ~96M on @BinanceChain ). (Previously we only counted the loss on @ethereum). And here is the list of affected assets/amounts on @BinanceChain pic.twitter.com/cXXApDFtd7

— PeckShield Inc. (@peckshield) December 5, 2021

The hackers made out with a mix of over 20 tokens that includes altcoins such as BNB, Safemoon, BSC-USD and BPay. Sizable amounts of meme coins such as BabyDoge, Floki and Moonshot were also compromised in the hack. 
According to Peckshield, the hack was a straightforward case of transfer-out, swap, and wash: