European stock markets erased early gains on Monday as a slide in oil prices hammered energy stocks, with investors also bracing for the worst corporate quarterly earnings season since the 2008 financial crisis due to the coronavirus pandemic.

The pan-European STOXX 600 index was down 1% after gaining as much as half a percent in early trading, with the energy sector posting its fourth decline in five sessions.

Total SA, BP Plc and Royal Dutch Shell Plc were among the biggest drags on the benchmark index, as oil prices fell to levels last seen in 1999 on oversupply concerns. The STOXX 600 has recovered about 23% since hitting an eight-year low in March on dramatic fiscal and monetary stimulus around the world, but still remains 31% away from reclaiming its record high as evidence of the economic hit from the pandemic piles up.

Dutch health technology company Philips rose 4.5% after saying sales and profit margins could still rise in 2020 if the coronavirus pandemic eases in the coming months and hospitals are able to restart elective surgeries, even as it pulled its forecast for the year.

Healthcare was the only sector trading higher as Novartis won the go-ahead from the US Food and Drug Administration to conduct a randomized trial of malaria drug hydroxychloroquine against COVID-19.

Readings on April manufacturing from across the world are due on Thursday and are expected to hit recession-era lows. French media conglomerate Vivendi jumped 3.4% after reporting a higher first-quarter revenue, led by its music division Universal.