Experimental Design Details
Our experiment follows six stages, with a total of 5 treatment conditions:
1. First, we implement an online survey with 3800 survey respondents, collecting baseline covariates and pre-treatment measures of our primary outcomes of interest.
2. We then block randomize respondents (stratifying sequentially based on party ID, experience in financial markets, sex, region, risk tolerance (above and below median), liquid assets (above and below median), and salience of climate change (above and median) as a policy priority) into one of three initial conditions (63% of the sample will be assigned to conditions a-b):
a. Invitation to participate in a six-week trading platform with an endowment of “Green Stocks,” with real or mock-up portfolios ranging in value from about $0 to $100.
b. Invitation to participate in a six-week trading platform with an endowment of “Brown Stocks”with real or mock-up portfolios ranging in value from about $0 to $100.
c. Empty control (no invitation to participate in the trading platform).
In conditions a-b, portfolio composition is randomly selected to include 3 out of 4 initial assets.
After informing respondents from groups a-b about the trading platform, we will invite participants from groups a-b to participate in a weekly survey on the platform in which they can receive information about their stock performance and buy and sell stocks within their treatment condition (e.g., if assigned green stocks, respondents will be able to buy and sell stocks from a curated list of green stocks, including an index fund). We will collect data on respondents’ trading behavior on the platform.
3. After 3 weeks of trading, and before the fourth trading session, we implement our midline survey among all study participants (including the empty control) in which we collect our primary attitudinal and behavioral measures relating to climate beliefs, attitudes, preferences, and behaviors.
4. On the fourth week of trading, we open up trading across sectors (Brown/Green). Then on the fifth week, we randomize respondents from treatment groups a-b to receive access to either i) financial disclosures about their assets or ii) financial and climate-related disclosures about their assets. Our primary objective here is to i) measure whether respondents consume the information disclosed, ii) identify the effects of random assignment to climate disclosures on trading behavior, and iii) identify the effects of climate disclosures on climate beliefs, attitudes, and behaviors in future surveys.
5. We plan the final week of trading (with the disclosure treatment) to occur following the 2024 US election. In each trading session following the start of disclosures, respondents will receive access to disclosures in accordance with their initial treatment status, and we will examine whether demand for and responses to exposure differ before and after the election, which is likely to determine the trajectory of future climate change policies in the US.
6. After six weeks of trading we implement an endline survey collecting all our outcomes of interest. We will also implement a long-term endline 3-months post-treatment.
Our primary specifications will compare: i) allocation of any stock with real value relative to control, ii) testing for differences in treatment effects for green vs. brown stocks relative to control, iii) testing for the impact of disclosure vs. not, iv) testing whether the treatment effects of disclosure vary by green vs. brown stocks.
To test the mechanism, we will also vary the value of the portfolio, including having a `fantasy' treatment, which we anticipate will have weaker effects. For secondary analysis, we will test whether the value of the portfolio impacts the treatment effects.
To correct for potential imbalances ex post, if necessary, we will use double-lasso procedures as suggested by Belloni, Chernozhukov and Hansen 2014 and Duflo et al. 2020.
Hypotheses:
1) We hypothesize that exposure to green stock portfolios will have a more positive impact on climate change knowledge, beliefs and support for climate mitigation policies, relative to control and to brown portfolios.
2) We further hypothesize that disclosures that making salient the adverse environmental impacts and associated risks of brown companies relative to green companies may also reduce the relative demand for brown company stock and their impact on attitudes.
3) Climate disclosure of green companies may in contrast strengthen the demand for green stocks, and the effects of green exposure.
4) Consumption of climate risk disclosures will increase (decrease) with a Democratic (Republican) presidential victory.
5) We will also examine whether stock exposures enhance financial literacy, reduce affective political polarization, enhance trust, as well as increase turnout.
Heterogeneous Treatment Effects
We will also examine heterogeneous treatment effects by:
i) Pre-treatment climate preferences and prior beliefs about the climate-related risk of the assigned stocks.
ii) Pre-treatment Party ID, affective polarization and trust
iii) Pre-treatment experience in financial markets
iv) Risk tolerance
v) Proximity to recent extreme weather events or natural disasters (if any)
vi) Stock price performance
vii) Pre-treatment geographical proximity to fossil fuel industries or those affected by (or likely to affected by) the green transition.