Analyze the relationship between 'Martin Winterkorn' and 'Chief Executive Officer' within the context of the input sentence.
Options: manufacturer, brand, currency, position held

The crisis wiped about 20 billion euros ($22.4 billion) off VW’s market value this week, forcing Chief Executive Officer Martin Winterkorn to step down on Wednesday as the scandal widened and opened the door for the exit of other top executives.
position held