Pfizer CEO Albert Bourla sold $5.6 million of his stock in the US pharmaceutical company on the same day it announced promising results for its Covid-19 vaccine candidate, filings showed Wednesday.

The company, however, has reportedly said the sale was part of a pre-arranged periodic divestment plan when the stock reaches a certain price.

According to a disclosure with US market regulator SEC, Bourla sold 132,508 shares at $41.94 each on Monday.

An executive vice president at the company, Sally Susman, also sold around $1.8 million in stock, or 43,662 shares.

Pfizer shares rose by more than seven per cent after peaking at over 15 per cent on Monday, when Bourla announced that trials so far had shown its vaccine candidate being developed with German company BioNTech was 90 per cent effective.

The company is yet to respond to a request for a comment from AFP, but a spokesman quoted by CNN described the sales as prearranged.

Sales at that price were previously scheduled as part of their personal financial management, the company said.

Such plans are designed to shield executives from insider trading accusations.

(AFP)