Shares of Twitter Inc. dropped 1.9% in premarket trade Wednesday, after the social media company said it plans a $1.0 billion convertible debt offering. The debt will be convertible to common stock, cash or a combination thereof at Twitter's election. The interest rate and initial conversion rate will be determined when the notes are priced. The notes will be offered to qualified institutional investors. The company expects to use some of the proceeds to pay for the convertible note hedge transaction, and the rest for general corporate purposes. The hedge transactions could include privately negotiated transactions to reduce the potential dilution to common stock or offset cash payments depending on what the notes will be converted into. The stock had run up 5.1% on Tuesday to stretch its win streak to nine sessions and close at a three-year high, after S&P Dow Jones Indices said it would add the stock to the S&P 500 The stock had rocketed 66% year to date through Wednesday, while the S&P 500 had gained 2.8%.