(Corrects days in paragraph 2 to Wednesday and Thursday, not Tuesday and Wednesday)
LONDON, Aug 15 (Reuters) - The U.S. yield curve was inverted for the second straight trading session on Thursday, as investors' concerns that the world's biggest economy could be heading for recession deepened.
Two-year U.S. borrowing costs fell below 10-year costs for the first time since 2007 on Wednesday, and the gap between the two was last at -0.91 basis points on Thursday.
Thirty year U.S. Treasury yields hit a new low of 1.98% , having fallen 27 basis points this week, the biggest one-week fall since May 2012. (Reporting by Virginia Furness Editing by Tommy Wilkes)