Steep falls from microprocessor heavyweights Imaginations Technologies and ARM Holdings sent the UK technology sector lower on Thursday.Imagination was down 5.6% at 193.7p before the close of trade, as the stock pulled back after an impressive 25% run over the last month.Nevertheless, including today's fall the stock has now fallen by 23% over the past six months and is nearly 60% lower than where it was last year.Analysts at Liberum Capital, while recommending investors 'buy' the stock, explained that the market is "now overly fearful of the threat from ARM's graphic business".However, the broker still kept its 250p target price which represents decent upside still from current prices.Liberum said: "We believe Imagination was overhyped on the way up and has been oversold on the way down. The longer-term opportunity hasn't fundamentally changed despite the share price move."In contrast, ARM has fallen sharply over the last month and was continuing its recent decline this afternoon, down 2.9% at 974.5p before the close. The stock has dropped over 12% since the end of December but is still nearly 9% than where it was six months ago.Others in the sector including IQE Telit Communications, Pace, CSR and Spirent Communications were also trading lower today.Top performing sectors so far todayHealth Care Equipment & Services 5,024.56 +0.67%Forestry & Paper 10,502.07 +0.62%Bottom performing sectors so far todayTechnology Hardware & Equipment 1,156.70 -2.96%Media 6,280.37 -2.44%Industrial Metals & Mining 1,252.20 -1.90%Oil Equipment, Services & Distribution 21,607.85 -1.71%Beverages 14,273.63 -1.45%BC