The Financial Post reports in its Friday edition that the stock market rebound lacked conviction, driven by aggressive short covering and low liquidity despite high trading volumes. A Bloomberg dispatch to the Post reports that traders closed short positions after President Donald Trump's tariff reprieve. Meantime, Goldman Sachs' noted that the S&P 500 futures liquidity had hit an all-time low, amplifying market moves. The S&P 500 soared 9.5 per cent, its best day since October, 2008, but contracts fell 2.1 per cent at 5 a.m. in New York. "The rally was exacerbated by technical factors and short covering, given the deep sell-off seen since April 2," said JPMorgan Market Intelligence analysts led by Andrew Tyler, warning that visibility is still very low for investors with further escalation on the U.S.-China trade war and additional tariffs on sectors such as pharmaceuticals still a possibility. On Wednesday, about 30 billion shares were traded on U.S. exchanges, the highest in nearly 17 years, said Bloomberg. Last week, hedge funds recorded their highest weekly short bets on U.S. macro products. On Wednesday, Goldman Sachs's most-shorted stocks rose over 12 per cent, surpassing the S&P 500's gain.