"集团内交易" can be translated into English as "intra-group transactions" or "intercompany transactions within the group".
"Intra-group transactions" is a more concise and commonly used term in financial and business contexts.
"Intercompany transactions within the group" provides a slightly more detailed description, emphasizing that the transactions occur between companies within the same group.
Both expressions are accurate and can be used depending on the specific context and desired level of detail.