TD Ameritrade placed its own logo in the form of an ASCII flag directly in the bitcoin blockchain. This is reported by CoinDesk.
The online broker used the OP_Return function in the bitcoin protocol to insert the required symbols, and included them in the blockchaain by sending 68 transactions. The peculiarity of blockchain technology ensures that this flag will remain forever in the public register of bitcoin.
We love finding new ways to use emerging technology. So we decided to have a little fun and plant our flag. Okay - technically, we embedded it. With a part of the blockchain called OP_Return, which functions like the memo space on a check, simple messages and characters can be placed within transactions on the blockchain. By linking 68 individual transactions, with 80 characters per transaction, we were able to create the larger image.
According to Blockchain. info, bitcoins were not transferred during these transactions.
OP_Return function was introduced in 2013. It allows users to leave their messages in the blockchain. In the notes to the Bitcoin Core 0.9 release it was said that developers do not welcome the storage of data not directly related to transactions in the public registry. According to them, "it is less expensive and much more efficient to store such data in some other place".