The 499 companies account for 97 per cent of the 516 firms listed on the Stock Exchange of Thailand and the Market for Alternative Investment (MAI). Of the 499, 462 are listed on the SET, the rest on the MAI. SET executive vice president Suthichai Chitvanich said in a statement that the 462 SET-listed firms posted a combined first-half net profit of Bt272.6 billion, representing a 7-per-cent year-on-year increase.

They had a combined revenue of Bt2.7 billion in the first half, up 22 per cent from the corresponding period last year.

Of the 462, 377 companies - or 82 per cent of the SET's listed firms - posted net profits.

The SET had earlier reported that the 482 companies listed on both the SET and the MAI posted a combined net profit of Bt145.28 billion, up 8 per cent on the year.

The net profit of the companies in the SET50 index accounted for 78 per cent of the 499 companies' total earnings, he said, adding that their net profit had increased by 13 per cent year on year.

Their combined gross margin in the period averaged 23 per cent.

Suthichai said the combined first-half net profit of the companies in the SET100 index represented 82 per cent of the 499 listed companies' earnings.

The top five performers in the first half were PTT Plc, Siam Cement Plc, PTT Exploration and Production Plc, Thai Oil Plc, and Advanced Info Service Plc. PTT's first-half net profit jumped 25 per cent to Bt55.38 billion, thanks to the spike in energy prices and the strong baht. In addition, the national oil and gas firm booked gains from the sale of its shares in Rayong Refinery through an initial public offering in June.