Since its peak in first quarter 2000, the volume of daily stock trades executed online has slumped dramatically--about 40 percent. Nonetheless, online trading firms are still spending money to update their technology and to attract new customers. By 2005, financial institutions are expected to have spent $11 billion to update their online-brokerage tech, according to Celent Communications, a financial research firm. To build brand awareness, discount online brokerages have also been forced to spend more money than established full-service firms for each new customer. One service upgrade has been wireless trading, which more than half of discount brokerages and one-third of full-service firms now offer, according to Deloitte & Touche. But few customers are taking advantage of it: only 3.8 percent of discount-brokerage customers and 0.1 percent of full-service customers trade with a device other than a computer. Write to letters@redherring.com.