The cost of options hedges against more gains in Treasuries surged to its highest level since March on Thursday, as investors sought the safety of US government bonds following a spike in oil prices and a deepening fiscal crisis in France.

Yields on the benchmark 10-year Treasury fell below 5% for the first time in about a month, with traders shelling out millions to hedge against an even deeper decline.

One measure shows market participants paying a higher premium for call options on longer-dated Treasuries over put options for the first time in seven months — suggesting that they are preparing for bonds to rally further.

See related: Risk of Bond Squeeze Builds as Trend-Following Quants Stay Short The moves come as a confluence of worrying events has undercut the bearish case for bonds, including a spike in oil prices on worries over more conflict in the Middle East and jitters over the artificial intelligence trade.

Meanwhile, French bond stress intensified as the threat of another round of weekend protests reinforced the country’s status as the weak link in global markets.

Standout positions on Thursday included one trade looking to target a drop in the 10-year yield to around 4.6% within a month.

The position has been built over the morning session to a size of roughly 65,000 contracts for a premium of roughly $7 million. The bond rally is also getting a boost from investors rushing to cover short positions.

CME open interest data from Wednesday’s session showed a large build-up of long-bond futures risk, signaling fresh short positions that may be coming under stress during Thursday’s rally.