It has been a difficult time for anyone betting on oil. Climate change threatens long-term demand.
In the past year ample production, trade disputes and fears of an economic downturn have weighed on the price of crude.
On December 3rd Brent crude fell to $61 per barrel—18% below its April high.
Yet by mid-December forces were aligning to support oil prices again.
The Organisation of the Petroleum Exporting Countries (OPEC) and its allies agreed on December 6th to lower output by more than 2.1m barrels a day.
Adding to the optimism, Saudi Aramco, the world's biggest oil company, listed 1.5% of its shares.
On December 12th its market value surpassed an astonishing $2trn.
And on December 13th President Donald Trump announced a preliminary trade agreement with China.
That bumped oil prices higher. As The Economist went to press on December 18th, Brent crude had risen to $65.74.
Even so, oil gamblers are wrestling with two big uncertainties. The first concerns America's output.
The country pumped 17.8m barrels a day in November, compared with an average of 15.5m in 2018.
But investors have grown impatient with frackers' meagre profits.
The cost of capital for American exploration and production companies has jumped by about 50% since mid-2016, according to Goldman Sachs.
At the start of December 663 rigs were operating in America, about a quarter fewer than a year earlier.
America's oil output will not shrink in 2020, but its growth may slow. The question is when, and by how much.
The second uncertainty concerns whether the members of OPEC's 23-country expanded alliance will stick to their new deal.