Notebook: Online Broker Margin Rates Keep Rising

Net-stock volatility is forcing online brokers to keep raising their already elevated margin rates.

The rapid rise of many Internet stocks over the past six months, coupled with the spectacular decline of some, has prompted many online brokers to change how much they'll let investors borrow to buy stocks. They've done this by raising margin maintenance requirements, the minimum amount of equity an investor must have in an account as a percentage of a stock's value.

By January, some brokers had boosted margin maintenance requirements to 100% on some stocks, ending borrowing to buy them. In the past couple of months, several top brokers, including Charles Schwab (SCH Quote) and E*Trade (EGRP Quote), have expanded their restrictions. ...