Worldwide second-quarter sales of high-speed asymmetric digital subscriber line (ADSL) modems increased 59 percent over the prior quarter, according to a study by market research firm Cahners In-Stat Group. ADSL shipments will top 1 million by year-end, the study showed. Alcatel claims the top spot with 33 percent market share. Cable modem sales slowed somewhat, but still are expected to reach 2.6 million units shipped worldwide at the end of 1999. Motorola and Nortel led the field, the study found.