Glaxo said that Sir Paul, 68, who has just announced his retirement from the drug group, had exercised options on 71,600 shares in the company at pounds 3.78 a share.
He had then sold the same number of shares at pounds 5.86 a share.
The shares represent only a relatively small part of his total holding in the group, however. Glaxo's most recent set of accounts show Sir Paul had 590,848 options as at 30 June last year. At the same date he also owned 457,904 shares outright, worth pounds 2.7m at yesterday's price.
Sir Paul, who will cease all group executive responsibilities at the end of next month, but who will not step down from the board until November, is one of the UK's highest paid businessmen.
He earned more than pounds 1.4m in 1993, including a pounds 410,400 payment under Glaxo's rolling, four-year, performance-related bonus scheme.