Nalaka Godahewa took over as chief of the Securities and Exchange Commission on Wednesday evening.
The Colombo Stock Exchange's main index gained 1.29 percent, or 66 points, to 5,180.15, its highest close since May 21. The market has fallen 14.72 percent this year.
"Mostly local retail trade pushed the bourse up," said a stock broker who declined to be identified.
Turnover was 554 million Sri Lanka rupees ($4.19 million), less than this year's daily average of 864 million rupees.
Foreign investors bought a net 20.4 million rupees worth of shares, extending the net foreign inflow this year to 28.42 billion rupees.
The rupee closed a tad firmer at 132.25/30 against the dollar from Wednesday's close of 132.35/45 as banks sold dollars, dealers said.
Stock and foreign exchange markets will be closed on Friday for a Buddhist religious holiday. Normal trading will resume on Monday. ($1 = 132.3500 Sri Lanka rupees)
(Reporting by Ranga Sirilal; Editing by Jeremy Laurence)