Shares in Barclays are higher this morning on speculation that the bank is considering offers for its asset management arm, Barclays Global Investors. It is, however, still quite a way short of this year's high posted last week at around 307p. Since we made these highs, the share price slipped back to support at 235p, mentioned earlier this week, before rallying yesterday, and jumping again on today's news.From a technical standpoint, however, the levels above 310p could well be a tough nut to crack. There are two important Fibonacci retracement levels between 310p and 324p. Firstly, the overall decline from the February 2007 highs at 773.25p to the January lows at 47.30p has a 38.2% Fibonacci resistance level at 324.50p. Secondly, the decline from the September 2008 highs at 475p, to the same lows, has a 61.8% Fibonacci retracement level at 311.50p.This convergence of fibonacci levels means that this area becomes increasingly significant from a chartist's point of view. For sentiment to remain positive over the coming weeks, the charts suggest that we would need to stay above trend line support, from the March lows and push up through this zone of resistance. For periodic TA updates follow me on TwitterAlso read my Investors Guide to Technical Analysis and Level 2