BUZZ-Tullow Oil: Citi turns bullish
** Tullow Oil (LSE: TLW.L - news) up as much as 6.8 pct after Citi upgrades to buy and raised PT to 433 pence
** Says concerns around the co's balance sheet and the key TEN development in Ghana "are more than discounted in the current valuation"
** Tullow top gainer on the midcap FTSE 250 index, with more than a full day's average volume traded in the first half hour. Stock rising for fourth consecutive day
** "We see Tullow's E&P growth as well positioned on the cost curve, with an average oil price breakeven of $45 per barrel," Citi says (abhiram.nandakumar.thomsonreuters.com@reuters.net)