BP completed the $6bn sale of a majority stake in Castrol on Monday, but a sharp fall in crude prices dragged its shares 4.37% lower and into the FTSE 100's bottom three.

A milestone lost in the oil slide

For BP (LSE:BP.), Monday 2 November 2026 should have been about a deal. The group completed the sale of a 65% stake in Castrol to Stonepeak Partners for $6bn. Instead, its shares spent the day tracking the oil price, closing down 4.37%. Some reports rounded the fall to 4.4%.

That left BP as the second-biggest faller in the FTSE 100. Only Ithaca Energy (LSE:ITH), down 5.94%, fared worse. Shell (LSE:SHEL) completed the bottom three with a 2.86% drop.

The wider index, by contrast, had a positive day. The FTSE 100 closed at 10,761.33, up 31.55 points, or 0.3%, extending its winning streak to four sessions. BP's share price moved sharply against that tide. The index itself took time to find its footing: at 12:15pm GMT it was essentially flat at 10,724.58, before recovering through the afternoon as buyers favoured consumer and travel stocks over oil producers.

Why oil, not Castrol, set the tone

Reports attributed BP's fall to lower oil prices, and the move in crude was hard to ignore. Brent fell to $105.09 a barrel at the London close, from $117.61 on Friday, a drop of about $12.52. Brent settled 7.63% lower at $104.77 in the US session, while West Texas Intermediate settled 7.36% lower at $96.46, its biggest one-day decline since 27 July.

The slide followed a cluster of diplomatic signals. Reports said Washington and Tehran were considering renewed, indirect negotiations, and talks between Iran and Qatar raised hopes of an end to the US–Iran conflict. Iran was also reported to have offered to reopen the Strait of Hormuz under strict conditions.

BP was caught up in a sector-wide sell-off. The FTSE 350 energy sector fell 3.3%, and all three of the FTSE 100's biggest fallers were oil names. The reports used here do not link BP's decline to the Castrol transaction itself; they tie it to the oil price.

The index-level effect matters too. The FTSE 100 is weighted by market capitalisation, so heavyweights such as BP and Shell move the benchmark more than smaller members. Their falls on Monday acted as a meaningful brake on the index, which still rose thanks to gains elsewhere.

Those gains came largely from companies that benefit when fuel is cheaper. Lower oil was seen as supporting consumer-facing firms through lower transport costs, midday market commentary said. Travel and leisure rose 2.7%, construction and materials 2.8% and consumer goods and services 2.5%. International Consolidated Airlines Group (LSE:IAG) rose 3.8%, and JD Sports Fashion (LSE:JD.) topped the index, up 4.76%, although no company-specific news was reported for JD Sports.

The Castrol deal by the numbers

Strip away the share price move, and the deal itself is clear-cut. BP has sold 65% of Castrol to Stonepeak Partners for $6bn. It keeps the remaining 35%, which is subject to a two-year lock-up. That means BP retains a meaningful economic interest in the business, but cannot sell that stake during the lock-up period.

The lubricants maker also has new Leadership at board level. Ben van Beurden, the former chief executive of Shell, has been appointed chair of Castrol's new board. The appointment brings a familiar name from the oil industry to the top of the business.

Illustration: if $6bn buys 65% of Castrol, then 100% of the Business would be valued at about $9.23bn on the same basis ($6bn divided by 0.65). BP's retained 35% would correspond to roughly $3.23bn at that implied value ($9.23bn multiplied by 0.35). This is simple arithmetic based on the deal price, not a valuation of BP's stake, and the actual value of the holding could differ, particularly given the two-year lock-up.

The reports used here do not set out what BP intends to do with the proceeds, and no figures beyond the $6bn price, the 65% sale and the 35% retained stake have been verified. Any further detail, such as how the deal affects BP's balance sheet, would need to come from the company itself.

Elsewhere in the sector's calendar, Shell, BP's FTSE 100 peer, is set to go ex-dividend on Thursday 12 November for a quarterly Dividend of 39.06 US cents, payable on Monday 21 December. That date is among a cluster of FTSE 100 ex-dividend dates falling on 12 November.

Beyond oil, BP's shares face the same macro calendar as the rest of the market. The Bank of England announces its rate decision on Thursday 5 November, with Bank Rate at 3.75% and a quarter-point rise to 4% widely expected; markets price that at about 95%. It would be the first increase in more than three years. The US holds midterm elections on Tuesday and publishes October payrolls on Friday.

Then there is the diplomatic track. Iranian Foreign Ministry spokesman Esmaeil Baghaei said "the ball is now in the US's court". Iran's Revolutionary Guards, meanwhile, said 11 tankers they accused of breaching navigational rules had caught fire in the Strait of Hormuz since 25 October. How those threads develop could determine whether Monday's oil slide deepens or reverses.

Key dates to watch

  • Tuesday 3 November: US midterm elections
  • Thursday 5 November: Bank of England rate decision
  • Friday 6 November: US October payrolls
  • Thursday 12 November: Shell goes ex-dividend at 39.06 US cents
  • Wednesday 2 December: December FTSE index review announced after the UK close

The bottom line

BP closed its $6bn Castrol deal on Monday, selling 65% to Stonepeak Partners and keeping a locked-up 35% stake, yet its shares fell 4.37% as Brent slid by about $12.52. Reports put the decline down to lower oil, not the transaction. With Iran–US diplomacy still in flux and a likely rate rise on Thursday, investors will be watching whether the oil price, rather than corporate milestones, continues to set the direction for BP in the FTSE 100.