Yahoo! has told the US Securities and Exchange Commission that it needs more time to hammer out its search deal with one-time rival Microsoft.

The SEC filing reads:

The Letter Agreement specified that the parties would execute Definitive Agreements by October 27, 2009, but given the complex nature of the transaction, there remain some details to be finalized. The parties are working diligently on finalizing the agreements, have made good progress to date, and have agreed to execute the agreements as expeditiously as possible.

No details are given as to the cause of the delay, but it is a feasible assumption that the two parties are working overtime to avoid possible regulatory scrutiny.