 Prologis Inc. PLD, -6.04 said Tuesday it is proposing to acquire Duke Realty Corp. DRE, -4.12 for 61.68 a share in an all-stock deal. Under the terms of the offer, Duke Realty shareholders would receive 0.466 shares of Prologis, valued at 61.68, or a premium of 29 over Dukes closing price on Monday. 