As of Tuesday, 482 of all 519 listed companies submitted their operating results for the April to June period.
Of the 482 firms, 81.32% reported profits for the second quarter.
Their combined turnover rose 7.69% to 2.85 trillion baht while earnings jumped 20.62% to 203.71 billion baht, said Paveena Sriphothong, a senior vice-president of the Stock Exchange of Thailand.
"The listed companies benefited from the world recovery in the second quarter, especially those in the energy and utilities sector which reaped a windfall from high oil prices, sales and foreign exchange profits," she said.
"Those focusing on overseas investment and exports such as food, electronic parts and construction materials continued to grow from the first quarter. However, those focusing on local consumption saw a slowdown.
"Overall, average gross profit margin in the second quarter was 18.82%, on par with last year's levels, while net profit margin was 7.15% compared to 6.38% year-on-year," she said.
Although the political situation stabilised in May and June, sales of listed companies were steady while net profit excluding extraordinary items fell by 6% from the previous quarter.
The affected sectors are transport, tourism, technology and IT.
The sectors which saw year-on-year increases in turnover and profits in both the second quarter and the first half were energy and utilities, banking and property.
Their combined first-half earnings were 244.44 billion baht, 57.32% of all net profits.
The companies with the highest retained earnings in the first half are: PTT, PTT Exploration and Production, Siam Commercial Bank, Kasikornbank and Bangkok Bank.
From January to June, the industries with the highest net incomes are resources, financial services and technology.