On Wednesday, the stock closed down 2.79% to 508.20 pence on the London Stock Exchange, in a balanced market.
Investors were digesting the announcement Tuesday night of the "resignation" with "immediate effect" of the former chief executive for lacking transparency on past intimate relationships with colleagues.
He spent less than four years at the helm of the oil major, one of the biggest names in British business.
Richard Hunter, an analyst at Interactive Investor, notes that "compared to the billions of dollars in fines that followed the Deepwater Horizon oil spill or negative oil prices during the pandemic, (...) this resignation is a surprise but not a major chapter in BP's history."
"There will inevitably be uncertainty about the interval required to find a permanent leader" or about a possible change in strategy, he adds.
Sophie Lund-Yates, an analyst at Hargreaves Lansdown, said "mistakes of this magnitude are not what is expected of one of the country's biggest bosses."
"A clear direction must be proclaimed quickly to limit the negative impact" on the company and its action, she continues.
Chief Financial Officer Murray Auchincloss is acting while a permanent replacement is sought. "The fundamentals have not changed," he said Wednesday in a message to staff.
"Our strategy has not changed. And we remain focused on performance, quarter after quarter," he added, stressing that the management team retains "the full support of the Board of Directors" to continue to implement its plan.
Bernard Looney can be credited with leading one of Britain's largest groups through the twists and turns of the pandemic, which caused oil prices and economic activity to collapse.
The Russian invasion of Ukraine, on the other hand, sent hydrocarbon prices soaring and inflated the accounts of oil companies, but resulted in an exit from activities in Russia and a colossal accounting burden of more than $24 billion.
Of Irish origin, Bernard Looney joined BP as an engineer in 1991 and has spent his entire career there, holding various operational and management positions in several countries, including the United States, Vietnam and the United Kingdom.
Mr Looney's departure comes on the heels of a wave of resignations or evictions in the British business community over sexual misconduct, including at Britain's largest employers' organisation, the CBI.
Analysts question what Looney's departure could mean for BP © Group's environmental strategy Glyn KIRK / AFP/Archives
As AJ Bell analyst Russ Mould notes, an internal investigation is still ongoing and "the concern" is that Tuesday night's revelations are a symptom of "broader problems with the corporate culture within BP".
Analysts also question what Looney's departure could mean for the group's environmental strategy.
Mr. Looney began his term by promising to lead the oil and gas giant to carbon neutrality, before an about-face in February, in the face of shareholder pressure in front of a stock price that has not returned to its pre-pandemic level and lags behind its competitors.
BP then indicated that it intended to increase its profits by 2030 by investing more in both renewables and hydrocarbons.
An unusual profile in the oil sector, Bernard Looney embodied a certain modernity by regularly feeding his Instagram account to describe the policies of the energy giant, especially in terms of diversity, or to chronicle his meetings with the group's staff around the world.
David Hewitt, an analyst at Liberum, argues that Mr Looney's abrupt departure could give BP an "opportunity to become the first oil +major+ to appoint a woman as chief executive".
The board has yet to decide what impact, if any, will be on Mr. Looney's remuneration of his hasty departure for breaches of his transparency obligations.
This had more than doubled last year, to 10 million pounds (11.3 million euros), in the wake of the surge in hydrocarbon prices, which had generated criticism, in view of the crisis of the cost of living in the United Kingdom.
© 2023 AFP