Updated with recent futures and stock-price information. Oil continued its free fall on Monday, plunging into $63 territory earlier. Light, sweet crude for August delivery was down $2.55 to $64.18 on the New York Mercantile Exchange. The price fell as low as $63.40 earlier with several reports pointing to economic uncertainty as the culprit. The contract settled at $66.73 last Thursday after losing $2.58 following the release of less-than-stellar unemployment figures. Markets were closed on Friday in observance of Independence Day in the U.S. On Thursday, many of the biggest oil and energy stocks took a hit and continued tracking in the red just after the opening bell this morning. Hess ( HES), which lost 6.5% on Thursday, was down another 3.7% on Monday morning. Marathon Oil ( MRO) was down 4.1% just after the opening bell. ConocoPhillips ( COP), Exxon Mobil ( XOM) and Chevron ( CVX) all languished in the early morning, losing 2.4%, 2.7% and 2.2%, respectively.