SDO/HMI line-of-sight magnetograms of AR 12741, with 720 s time resolution, as it traverses the solar disk. The AR is formed by a compact and elongated negative polarity followed by a very disperse positive field. An east-west light bridge (see white arrow) is clearly observed on the second panel dividing the preceding spot into two sections. MMFs, formed by small bipolar fragments, are seen moving towards the moat region surrounding the spot. The AR is continuously decaying; by 15 May other light bridges are observed (as shown in the third and fourth panels marked by white arrows). The last two panels correspond to the flare day, in the early morning and at night. Black corresponds to negative magnetic field (pointing away from the observer) and white to positive field (towards the observer), the values of the field have been saturated above (below) 1000 G (−1000 G). The images are centered in the main negative polarity with horizontal and vertical sizes of 300″ and 190″, respectively. The online movie HMI-8-17May.mp4 complements this figure.