How much is a block in trading?

Excuse me, could you please clarify what you mean by "a block in trading"? Are you referring to a block in the context of blockchain technology, which is a group of transactions that are bundled together and added to the blockchain as a single unit? Or are you referring to a different type of block that is relevant to trading, perhaps in the context of financial markets or a specific trading platform? Without more context, it's difficult to give a precise answer to your question. Could you please provide some additional information or clarify what you're asking about?