10 things you need to know before European markets open

Twitter results were released early and the stock crashed. Twitter's revenue hit $436 million (£284.16 million), missing expectations for $456 million, according to estimates from Bloomberg. Twitter stocks closed down -18%.

Big economic announcements are coming for the US. At 12:30 p.m. London time (8:30 a.m. ET) the US has its Q1 GDP figures. Analysts are expecting a big slowdown to around 1% annualised growth, due to the severe winter weather. At 7 p.m. London time (2 p.m. ET) the Fed will release its latest monetary policy announcement, offering signals of when the first post-crisis hike in interest rates might come.

David Cameron just pledged no new taxes if he wins in May. According to the Financial Times, Cameron wants to pass a law banning increases in income tax, national insurance or VAT until 2020, suggesting any fiscal consolidation would have to be practically all down to spending cuts.

Saudi Arabia has a new Crown Prince. Saudi King Salman bin Abdulaziz on Wednesday sacked his younger half brother as crown prince and appointed his nephew, Deputy Crown Prince Mohammed bin Nayef, as the new heir apparent, state television said.

Samsung net profit fell by nearly 40% in the first quarter. Samsung Electronics posted a 38.9% fall in first quarter net profit Wednesday, missing analyst estimates despite a surge in memory chip demand that cushioned a slump in smartphone sales.

But Samsung retook the title of world's biggest smartphone maker. Samsung Electronics overtook Apple to recapture the title of world's top smartphone maker by volume in the first quarter of 2015, research firm Strategy Analytics said on Wednesday.

EU Commission chief Jean Claude Juncker says the EU can reform to keep the UK in, but that freedom of movement is not negotiable. Juncker told the BBC that he believed Britain could find a compromise on reforming the European Union to keep it in the bloc but ruled out big changes to the open border policy that worries many Britons.

European lending and confidence data are coming. At 9 a.m. London time (4 a.m. ET) the eurozone's latest data on private lending is out, with analysts expecting a flat figure for March. Confidence figures for April are out at 10 a.m. London time (5 a.m. ET), and analysts expect them to stay largely static.

Asian stocks are mixed. Hong Kong's Hang Seng is down for a second day, currently 0.31% lower, while Japan's Nikkei is up 0.38%. The Shanghai Composite Index is basically flat, up 0.01%.

France's Dentressangle is being bought out by a US group. US transporter XPO Logistics announced a deal Tuesday to buy France's much larger Norbert Dentressangle in a deal worth €3.24 billion ($3.56 billion, £2.32 billion) including acquired debt.