Select brokerage firms are boosting the rates they pay on idle cash that’s just sitting in retail investors’ accounts. Since the Federal Reserve embarked on its policy-tightening campaign more than a year ago, yields on a range of otherwise boring investments have climbed, including short-term Treasury bills. This has spurred banks to boost rates on certificates of deposit and high-yield savings accounts to attract customers’ dollars. In fact, Goldman Sachs’ Marcus recently raised the annual percentage yield on its online savings account to 4.15%, making it even with the rate offered on Apple’s high-yield savings account. Brokerages have also entered the fray, with a few companies lifting the rates they offer on cash sweep accounts – which is where investors hold dollars that they haven’t yet committed toward purchasing investments. Vanguard recently boosted its cash sweep rate to 3.5% from 3.25%, Bank of America found, while Fidelity Investments is now offering a 2.6% rate on cash . Higher rates for some The firms have taken two strategies to contend with the higher rate environment, Bank of America analyst Craig Siegenthaler said in his May 10 report. The first is to keep rates low, which will allow them to expand their net interest margins while allowing clients the opportunity to seek attractive yields in other offerings, known as sorting, the analyst said. This move seems to be playing out at LPL Financial , he added. Consider that LPL raised its cash sweep rate by as much as 60 basis points for its wealthiest clients, Bank of America found. LPL’s insured cash account offers a rate of 2% – up from 1.40% – for investors with a household value exceeding $10 million. Rates are lower for more modest investors, with households in the $300,000 to $500,000 range eligible for a rate of 0.45%. The second is to raise rates to potentially attract deposits, even if it means lower net interest margins – which seems to be the playbook for Robinhood , Siegenthaler added. Subscribers to Robinhood Gold , a service that gives clients access to market research, offers a 4.65% interest rate on cash. Clients who don’t participate in Robinhood Gold are eligible for a 1.5% rate on their idle cash. So far, the move seems to be helping the firm attract dollars. “HOOD has continued to experience ‘reverse-sorting’ as clients are depositing more cash with the broker compared to most other brokers with lower rates that are losing deposits via sorting,” Siegenthaler said. – CNBC’s Michael Bloom contributed to this story.