NEW YORK—The first U.S. bitcoin futures-based exchange-traded fund (ETF) began trading on Tuesday, sending bitcoin to a six-month high and just off its all-time peak, as traders bet the ETF could boost investment flows into cryptocurrencies. The ProShares Bitcoin Strategy ETF closed up 2.59 percent at $41.94 in its first day of trading, with around $1 billion worth of shares trading hands on Intercontinental Exchange Inc.’s NYSE Arca exchange under the ticker BITO. The greenlighting of the ETF by the U.S. Securities and Exchange Commission (SEC) was seen as a watershed moment for cryptocurrencies and helped push the price of bitcoin as high as $64,367.14, its highest level since mid-April and near its record of $64,895.22. Bitcoin, the world’s largest cryptocurrency, is notoriously volatile, and has risen around 45 percent this month on hopes that the advent of U.S. bitcoin ETFs—several of which are in the works—will spur billions of …