The most extreme case is shown on the bottom right graph, where the utilities and energy sectors went from a near perfect correlation in 2011 to a somewhat negative correlation in 2017. (mindfullyinvesting.com)
In the lower right graph, hot nights are defined as nights with a minimum temperature higher than 98 % of the minimum temperatures between 1971 and 2000.» (washingtonpost.com)
You look at the right graph; there was a dividend cut between 2009 and 2010. (dividendstocksrock.com)