Exchange-traded funds with heavy exposure to social media stocks were lower Thursday after a high-profile hack of Twitter Inc. /zigman2/quotes/203180645/composite TWTR +0.43% ostensibly in connection to a Bitcoin scam. The Global X Social Media ETF /zigman2/quotes/202034985/composite SOCL +1.17% , which has 8.1% of its portfolio allocated to Twitter shares, was down 2% in the early afternoon, on track for its worst week since the havoc in the financial markets in March. The John Hancock Multifactor Media & Communications ETF /zigman2/quotes/209285373/composite JHCS +0.63% , with nearly 4% of its holdings in Twitter, was off 0.2%. Twitter shares fell sharply overnight, but by early afternoon were off only 1.1%. Despite Thursday's loss, and another steep sell-off July 13, Twitter shares are on track for their best month since last July, according to FactSet data.