(Bloomberg) -- If history is any guide, investment-grade US corporate bonds can stay at current nosebleed valuations for months more. Most Read from BloombergTrumpism Is Emptying ChurchesIran’s Better, Stealthier Drones Are Remaking Global WarfareBlackstone Nears Buyout of Skin-Care Company L’OccitaneWhy India’s South Rejects Modi — And Why It MattersGermany to Order Ships, Armored Vehicles Worth Up to €7 BillionThat’s the conclusion of Barclays, which said that the present macro environment, an