Methodology

Data collection

The 2012 STOCK Act (Stop Trading on Congressional Knowledge Act) requires that senators, House members, and senior members of the executive branch disclose information on financial holdings and transactions. The law additionally requires that covered officials disclose information on financial holdings of spouses and dependents (e.g. children).

Senate data are collected from public disclosures posted on the Senate Financial Disclosure Database. Data on President Donald Trump’s disclosures are posted on the US Office of Government Ethics website. Two types of information are pulled: 1) Asset holdings from annual reports and 2) Asset transactions from periodic transaction reports. Some data can be processed programmatically, but data from some scanned paper filings has to be manually entered to ensure accuracy.

Data processing

Holdings and Transaction data are combined to construct a portfolio of assets that are held by each official on any given day since the later of January 1, 2014 or their first day in office. Stock holdings are reported in binned ranges, and we take the midpoint of each range as the estimated value (e.g. an official who reports buying $15,001 - $50,000 of AAPL is assumed to buy $32,500.50 of AAPL stock). All stocks owned by a household are included: own holdings, spousal holdings, and dependent holdings. If estimates imply negative holdings, we censor holdings at $0 (no net short positions).

Daily closing prices (adjusted for dividends and splits) of all publicly traded assets held by officials are pulled form Yahoo Finance along with industry classifications of companies. Exchange tickers are linked to all disclosed assets, so financial data can be linked even when an official does not include an asset’s ticker in the disclosure. Closing prices are used to calculate daily returns for each official’s stocks and their overall portfolios.

For financial holdings that are not publicly traded, we typically post unprocessed disclosures.

Aggregate senator index construction

The “all senate” index is constructed by equally weighting the returns of each senator’s asset portfolios. This means the returns of a wealthy senator with tens of millions invested in stocks impacts the index the same amount as the returns of a less wealth senator. A senator’s individual portfolio returns is included in the “all senate” index from 1/1/2014 or their first day in office (whichever is later) until their last day in office.