Bulgaria's ERG Capital-3 REIT has signed a preliminary contract for the sale of real estate worth 3.5 million euro ($4.1 million) on September 13, it said on Friday.The final contract is expected to be signed on November 15, the real estate investment trust said in a bourse filing.If certain arrangements in the preliminary contract are not fulfilled, the final contract may not be signed, ERG Capital-3 REIT noted.($ = 0.8574 euro)