As Vikram Pandit celebrates his first full-year profit as head of Citigroup, an old nemesis clouds the bank’s future: defective mortgages. Three years after bad home loans helped trigger the recession and six weeks after the government cashed in the last of its $45 billion Citigroup investment, the New York-based bank is still selling mortgages that violate quality standards, according to an internal Freddie Mac review obtained by Bloomberg. Fifteen percent of the performing loans Citigroup sold to the government-owned mortgage-finance company in the second half of 2009 and the first half of 2010 had such flaws as missing appraisals or insurance documents or income miscalculations, according to the review of 375 mortgages. The target for defects should be about 5%, said Tim Rood, a former executive with Freddie’s sister agency, Fannie Mae, and now managing director at Washington-based advisory firm Collingwood Group.