Sterling trims gains after setting three-week high

Sterling returned lower today after trimming the gains made after Fed Chair Janet Yellen's speech, which propelled it to a three-week high before sliding back as the dollar returned higher. 

GBP/USD last traded at 1.3185, down from the opening of 1.3195, with a two-week high at 1.3281, and a session-low at 1.3145. 

Sterling's wavering comes as the dollar dithers following Yellen's speech, with prospects of a rate hike rising but Yellen didn't put a specific data for such a hike. 

The pound is facing persistent resistance at 1.3270, which forced sterling down and stemmed its rise, specially as the dollar returned higher again versus major rivals. 

The dollar index, which tracks the greenback against an array of six main currencies, rose to 94.77 from the opening of 94.69, with a session-low at 94.23, and a high at 95.04, after the index hit its highest this week at 94.95.