Easing in corporate borrowing costs mid-April, which encouraged a wave of bond issuance, appears to be reversing as concerns over a prolonged conflict in West Asia drive yields higher once again. Firming local yields have made issuers more cautious, with some scaling back planned bond sales after a brief period of frenetic activity. Recent state-backed bond issuances show signs that borrowing costs may be beginning to edge higher again. SIDBI, which had planned to raise '6,000 crore through a three-year bond sale on Tuesday, mobilised only '3,025 crore at a yield of 7.61%. A week earlier, NABARD raised '4,250 crore against a planned '7,000 crore at 7.48% for a similar tenor.