London’s stock indexes fell on Monday after the U.S. moved to blockade Iranian shipping following the collapse of the weekend peace talks that dimmed hopes of a swift end to the Middle East conflict.The blue-chip FTSE 100 index fell 0.4% to 10,558.38 points by 0944 GMT, while the midcap FTSE 250 slipped 0.8%.London markets were swept up in a risk-off stance globally as failed U.S.-Iran talks pushed up oil prices to more than $100 a barrel again.The two indexes had logged gains last week after a two-week ceasefire between the U.S. and Iran, though the fragile truce showed signs of strain as fighting continued.Heavyweight banks came under pressure on Monday, with HSBC and Barclays leading the declines, down 1% and 1.3%, respectively.Energy stocks gained, with Shell and BP rising about 1.8% each.Travel and leisure stocks declined as oil prices jumped. Cruise operator Carnival was down 3.9%, while airlines also inched lower.EasyJet and Wizz Air fell 4.3% and 7.3%, respectively. Bernstein downgraded Wizz to “market-perform” from “outperform”.A report said Finance Minister Rachel Reeves would set out her approach to help businesses struggling with higher energy prices later this week, in the wake of the Middle East conflict.Homebuilder Vistry appointed insider Adam Daniels as CEO, but its shares fell 4.9% amid broader market Wise advanced 5.3% after the fintech group reported a 26% jump in fourth-quarter cross-border transaction volume.