TOKYO, July 6 (Reuters) - Japan's Nikkei share average touched a one-week low on Thursday, dragged down by chip-related firms as Socionext was set to hit its daily lower limit, after its biggest shareholders sold their entire stake in the fast-growing chip-design company.

By 0200 GMT, the Nikkei dropped 1.04% to 32,990.73, falling below 33,000 for the fist time since June 28. The broader Topix slipped 0.64% to 2,291.42

Socionext's shares were untraded, with a glut of sell orders and were set to fall to their daily limit after the company's top shareholders, including Panasonic Holdings and Development Bank of Japan, sold their entire stake worth 280 billion yen ($1.94 billion).

Socionext, which went public in October last year, surged nearly 280% this year, becoming one of the icons for chip-related shares that helped the Nikkei to reach a 33-year high.

"News on the sale of Socionext shares sent U.S. technology stocks down overnight, which pushed leading Japanese chip shares lower today," said Shigetoshi Kamada, general manager - research, Tachibana Securities.

"Socionext was among shares global investors bought to catch up the rally in the Nikkei."

Wall Street's main indexes ended slightly lower overnight, with the Philadelphia SE Semiconductor Index dropping 2.2%, while Intel slipped 3.3% and Texas Instruments declined 1.8%.

In Japan, chip-making equipment maker Tokyo Electron lost 2.84% and was the biggest drag on the Nikkei. Chip-testing equipment maker Advantest lost 1.45% and chip-maker Renesas Electronics lost 3.25%.

Sentiment was also weakened by asset managers selling shares worth more than 1 trillion yen in exchange traded funds ahead of their dividend distribution dates through the beginning of next week, said Shoichi Arisawa, general manager - investment research, IwaiCosmo Securities.

Steel maker Kobe Steel rose 2.28% to become the top gainer on the Nikkei. Energy explorers were the top performer among the Tokyo Stock Exchange's 33 industry subindxes, gaining 0.85%. ($1 = 144.3500 yen) (Reporting by Junko Fujita; Editing by Rashmi Aich)