STEP-BY-STEP ANSWER:
Step 1: Identify that financial intermediaries (e.g., banks, mutual funds) act as middlemen between savers and borrowers.
Step 2: Recognize that they aggregate funds from many small savers, which reduces the per-unit transaction costs compared to individual transactions.
Step 3: Understand that by pooling funds, they can diversify the risk across many investments or loans.
Step 4: Note that financial intermediaries also perform due diligence on borrowers, thereby reducing the effects of adverse selection and moral hazard.
Final Answer: Financial intermediaries reduce transaction costs through aggregation and diversification, and they mitigate information asymmetry, thereby efficiently sharing risk among market participants.