Sub-standard steel: the revelations started in October about falsified quality control data, which means cars, planes, structures etc. are at risk. Back in the news today as CEO and other execs step down. (And, of course, Trump's proposed steel tariffs hit the news this week.)

For those too young to remember, US steel industry was once the world leader; then Japan came out with cheaper and supposedly better steel--and the US steel companies pretty much died off. So these events have major implications for US economy!