3.1. Sample
We conduct our analysis using a new comprehensive dataset from Markit Data Explorer (DXL) spanning 114 months (July
2004–December 2013). DXL's data are collected from a consortium of more than 100 institutional lenders, who collectively
represent the largest pool of loanable equity inventory in the world. DXL coverage is expansive, as the universe of firms with
lending data represents 90% of the market capitalization of CRSP firms. For each stock in the database, DXL provides daily
measures of the total shares borrowed from DXL lenders (a demand measure), and the total lendable inventory available
from them (a supply measure). In addition, DXL computes a Daily Cost of Borrowing Score (DCBS), a measure of the relative
cost of borrowing for each stock, ranging from 1 (low cost) to 10 (high cost). For a subset of firms, DXL also reports more
detailed information on actual rebate rates and loan fees.9
We use the pricing information in the DXL data to develop a simple measure of supply slack. Specifically, using the subset
of observations with loan fee data, we show that DCBS values of 1 and 2 correspond to stocks that are easy to borrow as
defined in prior research (annualized loan fees below 100 basis points). Following this logic, we define a Special (hard-toborrow)
stock as one with a DCBS of 3 or larger.10 By this definition, 14.3% of our firm-month observations are categorized as
Special and 85.7% as General Collateral (GC; easy-to-borrow).