Artisan Partners publicly opposed Axalta proposed all-stock merger with AkzoNobel, calling the deal a clear no and arguing Axalta would be trading a strong, undervalued business for a weaker one. The firm, which owns under 1% of Axalta, has a history of hard-hitting campaigns, including CEO ousters at Credit Suisse and Danone. The merger would create a $25-billion coatings giant.