Twitter Inc. said Wednesday it plans to sell at least $1 billion in bonds that convert to equity, joining a rush of tech companies taking advantage of soaring share prices to issue convertible debt.

The move comes as Twitter shares have surged to three-year highs after S&P Dow Jones Indices said the company would be added to the S&P 500 before the start of trading Thursday. The shares on Wednesday rose 0.8% to $40.10, their highest close since April 2015.