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Finding Historical Stock Borrow Costs and Availability Data

Article Quant Q&A · Author: Stacey
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Summary

The document addresses how equity traders can obtain historical stock borrow rates to account for short-selling costs when evaluating strategy positions. It explains that rates for hard-to-borrow securities often depend on each broker’s balance sheet, funding sources, and current inventory, so a universal historical series may be difficult to find. Broker portals and financial data services are likely sources for those broker-specific rates.

For general-collateral borrowing, the answer points to New York Fed rate data and suggests that historical rates might be approximated by adding a spread to a reference rate. A second answer identifies a service with time series for borrowing costs and share availability sourced from Interactive Brokers. These suggestions provide possible starting points, but the document gives no direct comparison of coverage, data quality, access terms, or historical depth. The spread-based approach is an approximation and may not represent a particular broker’s actual financing costs, especially for securities with constrained supply.

Key ideas

  • Borrow rates for hard-to-borrow stocks can vary by broker and funding conditions.
  • General-collateral rates may be available from central bank data sources.
  • A reference rate plus a spread can serve as a rough historical borrow-cost estimate.
  • Some services provide borrow-cost and share-availability time series based on broker data.

Tags

EquitiesExecutionRisk managementUS markets
Full text
# Stock borrow cost timeseries


# Stock borrow cost timeseries












I am looking to increase the robustness of some equity strategies that I am working on. Apart (maybe) from brokers is there anywhere online (and preferably for free) that has historic stock borrow percentages or abosulte borrow costs available for borrowing stocks? I want to factor the cost of borrowing a stock into whether I want to take a position (if the cost is high then there maybe not enough alpha to justify the position to be taken etc).

Thanks

## Answer by R110 (score 6)

https://quant.stackexchange.com/a/61950

Unfortunately this data is usually very broker specific -- not least because a firm's borrow rates will be tied to its balance sheet, flows, repos, where it's able to currently finance its book (ie, is it a US, European or Asian bank) etc etc. As a result, anything that is not GC (General Collateral) borrow is going to be specific to the broker and, outside of Bloomberg or a broker portal, is going to be hard to find.

That said, you can download GC borrow rates from the New York Fed:

https://apps.newyorkfed.org/markets/autorates/bgcr

And, from there, you can probably bootstrap historical rates as some margin over LIBOR.

HTH.

## Answer by Helin (score 4)

https://quant.stackexchange.com/a/61962

This website has detailed time series data for borrowing cost and shares available, sourced from IB. You can also retrieve the data using the following API endpoint: `https://iborrowdesk.com/api/ticker/{symbol}` (replacing `{symbol}` with the proper symbol ticker).

Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.