Sources: Substack is raising $65M at a $650M valuation; a16z will lead the round (Axios)

Axios:
Sources: Substack is raising $65M at a $650M valuation; a16z will lead the round  —  Substack is raising $65 million in new venture capital funding that would value the company at around $650 million, Axios has learned.  Existing investor Andreessen Horowitz is leading the round.