Both the West Texas Intermediate (WTI) and Brent crude oil futures contracts started the week on a low note.

The March WTI lost $1.70 Monday to settle at $51.99 per barrel. The benchmark peaked at $53.64 and bottomed out at $51.33 during the early week session.

Brent crude oil for March delivery fell by a penny more than the WTI, shedding $1.71 to end the day at $59.93 per barrel.

“The price movement for WTI and Brent was largely due to the renewed concerns over supply as a result of a rise in U.S. oil rig counts,” a former Stout investment banker who now runs the value investing blog Millionaire Mob told Rigzone. “This is a key driver in implying higher future production. Extraction of oil in the prime basins such as the Permian are forecasted to increase slightly since breakeven costs remain below current oil prices.”

U.S. weekly rig counts are above 1,000, compared to 450 in mid-February of 2016, the blog founder added.

The price of a gallon of reformulated gasoline (RBOB) also declined Monday. February RBOB futures dropped by nearly 6 cents, setting at $1.33.

Despite frigid temperatures set to envelop much of the continental United States this week, Henry Hub natural gas futures posted a sharp loss and fell below the $3-mark Monday. The February Henry Hub price settled at $2.91, reflecting a nearly 27-cent decline for the day.

“Henry Hub futures prices are down today as a result of similar news with the WTI and Brent,” the value investing pro said. “Specifically, horizontal rigs were up three on the week and were up 124 on the year.”