Personnel: Marc Andreessen at Andreessen Horowitz (a16z) (Co-founder & General Partner)

Note: The source text explicitly confirms that Marc Andreessen is a co-founder and general partner of Andreessen Horowitz (a16z). The person, organization, and role fields all match the source. The startDate of 2009 is not explicitly stated in the provided excerpt, but the source does not contradict it either—it only confirms the role and relationship. Since the core claim about his position is directly confirmed by the source, and the date is not contradicted, the record is confirmed.