(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window) * Oil majors down as oil prices drop * IG tumbles on tastytrade buyout plan * Ibstock soars after upbeat outlook * FTSE 100, FTSE 250 shed 0.4% (Updates to market close; Adds details, comment) Jan 21 (Reuters) - London’s FTSE 100 slipped on Thursday, weighed down by falls in energy stocks as oil prices slid after a surprise increase in U.S. crude inventories, while IG Group tumbled on plans to buy U.S. trading platform tastytrade for $1 billion. The blue-chip FTSE 100 index lost 0.4%, while the domestically focussed mid-cap FTSE 250 index also slid 0.4%. Energy majors BP and Royal Dutch Shell fell 3.2% and 2.5%, respectively, and were the biggest drags on the FTSE-100 index. “What is holding back the UK is a lack of tech stocks to capture the ‘rotation’ back into tech seen since Netflix results,” said Chris Beauchamp, chief market analyst at IG. “Stock markets overall are much quieter today, looking so far in vain for a new catalyst for further upside.” The FTSE 100 shed 14.3% in value last year, its worst performance since a 31% plunge in 2008 and underperforming its European peers by a wide margin, as pandemic-driven lockdowns battered the economy and led to mass layoffs. British Prime Minister Boris Johnson said it was too early to say when the national coronavirus lockdown in England would end, as daily deaths from COVID-19 reach new highs and hospitals become increasingly stretched. IG Group tumbled 8.5% after announcing plans to buy tastytrade, venturing into North America after a stellar year for the new breed of retail investment brokerages. Ibstock jumped 7.3% to the top of the FTSE 250 after the company said fourth-quarter activity benefited from better-than-expected demand for new houses and repairs. Pets at Home Group Plc rose 2.2% after reporting an 18% jump in third-quarter revenue, boosted by higher demand for its accessories and veterinary services as more people adopted pets during lockdowns. (Reporting by Shivani Kumaresan in Bengaluru; editing by Uttaresh.V and Mark Potter)