FTC launches investigation into Instagram acquisition - The Federal Trade Commission has begun an investigation into Facebook’s acquisition of Instagram that could delay the closing of the deal. The investigation does not imply any wrongdoing. The agency looks into most mergers valued at more than $66 million. Facebook agreed to buy Instagram for $1 billion.

TBG study shows how Facebook ad CTR varies by industry – Ads for beauty and fitness brands had the highest clickthrough rate on Facebook, according to an analysis of billions of ad impressions from 235 TBG Digital clients in the past year. Finance-related ads had the lowest CTR. Other industries’ average CTRs by day can be seen to the right. This information can help companies benchmark their own success with Facebook ad campaigns.

Optimal launches free tool ranking brand pages - Optimal, Inc., the creators of Optim.al, a social media advertising and audience data platform, released its Optimal Index to rank brands on Facebook by a metric besides Likes. The index is calculated by taking a brand page’s engagement rate, multiplied by the weighted-average of Facebook’s cost per click estimate for the page, multiplied by the number of Likes the page has. Walmart is currently the highest-ranked page in the index.

Facebook releases ad preview tools - Facebook now offers developers an Action Spec Preview Tool to help them preview what Sponsored Stories for their apps will look like using the new action spec ad beta. Facebook also launched an ad preview API for previewing ads for existing ad groups, ad creatives and creative specifications.