Proactive Investors - AstraZeneca PLC (LON:AZN) shares were the biggest fallers on the FTSE 100 on Wednesday, down 3.6%, with no obvious reason for the sell-off.
News and broker comments on the Anglo-Swedish drug giant seemed positive, following the release of late-stage clinical trial data from the company the day before.
Citi said the data on trials involving AZ's three key growth drivers "should enable shares to move ahead after a prolonged period of uncertainty".
An update from Johnson & Johnson (NYSE:JNJ) on its MARIPOSA trial offers little downside risk to expectations for the London-listed group's blockbuster cancer drug Tagrisso, Citi and others said.
Those at Barclays (LON:BARC) said MARIPOSA "doesn't look like it meets the bar to steer patients away from Tagrisso" as a treatment for first-line non-small cell lung cancer.
Earlier in the week, AZ said a combination of Tagrisso with chemotherapy to treat a type of lung cancer had been accepted and granted priority review by the US Food and Drug Administration.
Ignoring the ongoing rumbles about legal claims from anti-vaxxers on social media, the only plausible negative for the company was potential read-across from fellow vaccine maker Pfizer (NYSE:PFE), which last Friday slashed its full-year earnings and revenue guidance as demand wanes for its Covid vaccines and other treatments.
Pfizer has not enjoyed much help from the rollout of its latest vaccine booster shot due to issues with supply, US insurance coverage, and lower demand.
Unlike its US rival, AZ produced a not-for-profit vaccine and last year withdrew its application to market any Covid vaccine in the US as it did not see sufficient demand, though it does have some other vaccines in the pipeline.