From the blog "Market News"

Expected index adjustments  Please see the expected dividend adjustment figures for a number of our major indices for the week commencing 21 Jan 2019. If you have any queries or questions on this please let us know in the comments section below. For further information regarding dividend adjustments, and how they affect  your positions, please take a look at the video.  NB: All dividend adjustments are forecasts and therefore speculative. A dividend adjustment is a cash neutral ad