Shares of Nio Inc. /zigman2/quotes/204905836/composite NIO -1.80% shot up 14% on heavy volume in morning trading Wednesday, as the China-based electric vehicle company was headed for a seventh-straight gain toward a record high. Trading volume ballooned to 129.2 million shares, making the stock the most actively traded on major U.S. exchanges, and already above the full-day average of 113.4 million shares. The stock has now more than doubled (up 118.1%) during its latest win streak, which would be the longest since its record nine-day win streak that ended Jan. 21. Nio's isn't the only EV maker's stock enjoying a burst of strength of late, as U.S.-based rival Tesla Inc. shares /zigman2/quotes/203558040/composite TSLA -0.82% are also rising toward a seventh-straight gain toward another record, and have gained 47.0% during their current win streak. The gains come as the both Tesla and Nio reported last week upbeat deliveries data. Nio's stock has rocketed more than fivefold (up 449.8%) year to date and Telsa shares have more than tripled (up 237.3%), while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.17% has slipped 1.9%.