Oct 28 (Reuters) - Teradyne on Tuesday forecast fourth-quarter revenue above Wall Street expectations, banking on robust demand for its chip-testing equipment, and named a new chief financial officer.

Shares of the company surged more than 21% in extended trading, after it also surpassed estimates for third-quarter revenue.

Teradyne said Michelle Turner, former CFO at defense contractor L3Harris Technologies LHX.N, has been appointed as its finance chief effective November 3. Turner will succeed Sanjay Mehta, who has been the company's CFO since 2019 and plans to retire in 2026.

It forecast fourth-quarter revenue to be between $920 million and $1 billion, compared with analysts' average estimate of $814.3 million, according to data compiled by LSEG.

The upbeat outlook underscores how the artificial intelligence investment boom is reverberating across the semiconductor supply chain, driving demand for companies such as Teradyne that provide testing and automation tools essential for chip quality assurance and mass production.

Teradyne's fourth-quarter sales are expected to increase 25% sequentially and 27% from the year earlier, CEO Greg Smith said.

The company also expects adjusted earnings per share to be between $1.20 and $1.46 for the fourth quarter, while analysts estimate $1.02.

Its third-quarter revenue of $769.2 million beat expectations of $743.8 million.