European equity markets were heading for a weaker open Wednesday as oil prices extended gains amid escalating Middle East tensions. The higher energy prices renewed inflation concerns and boosted expectations for interest-rate increases. Iran said it had struck two American vessels and eight oil tankers in the Gulf, retaliating for U.S. attacks on five Iranian tankers near Kharg Island. Investors were also positioning ahead of the European Central Bank (ECB), the euro-zone central bank, which was widely expected to raise rates by 25 basis points on Thursday. In corporate news, Dutch semiconductor equipment maker ASML secured commitments from major chipmakers to adopt its latest production technology as demand for more advanced AI hardware continued to surge. Euro Stoxx 50 and Stoxx 600 futures were each down about 0.4% in premarket trading.