{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/129561"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/129561","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Essays on retail trading and credit cards","abstract":"Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01","abstract_html":"Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01","abstract_has_math":false,"creators":["Mohr, Justin"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Finance","degree_department":null,"school":null,"contributors":["Pennacchi, George","Kahn, Charlie","Kiku, Dana","Xu, Qiping","Fonseca, Julia"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-04-23","date_published":"2025-04-23","updated_at":"2026-07-22T22:25:05Z","subjects":["Social media","Investor activity","Information","Influencers","Belief formation","Payment Security","Consumer Credit","Fraud Risk","Credit Card","Lending","Credit Information","Household Finance"],"languages":["en","eng"],"rights":["© 2025 Justin Mohr"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/129561","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Pennacchi, George","Kahn, Charlie","Kiku, Dana","Xu, Qiping","Fonseca, Julia"]},{"key":"dc:creator","label":"Author","values":["Mohr, Justin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-04-23","2025-05"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Finance"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Social media","Investor activity","Information","Influencers","Belief formation","Payment Security","Consumer Credit","Fraud Risk","Credit Card","Lending","Credit Information","Household Finance"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["© 2025 Justin Mohr"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/129561"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01","The student, Justin Mohr, accepted the attached license on 2025-04-22 at 20:37.","The student, Justin Mohr, submitted this Dissertation for approval on 2025-04-22 at 20:57.","This Dissertation was approved for publication on 2025-04-23 at 14:28.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21906 on 2025-10-19 at 19:15:25","My dissertation focuses on retail trading and household finance. The abstracts of the three chapters are as follows: In Chapter 1, I use days on which social media platform connectivity is exogenously interrupted to study social media’s impact on retail trading. It provides evidence consistent with social media platforms spreading fanatical optimism rather than rational beliefs. On “outage” days, social media-discussed stocks experience an increase in retail trading volume concentrated in selling. Social media-discussed stocks experience a price decline that reverses over the subsequent day. These results can be explained by a theoretical model of fanatical optimism and are robust to a battery of alternative explanations. The paper’s findings highlight the important role of social media on retail traders’ belief formation and its stock market consequences. In Chapter 2, a joint work with Divij Kohli, we study credit card fraud. Credit card fraud is the most common type of identity fraud in the U.S. with a cost of over $11.64 billion. In 2014, the U.S. government pushed for widespread adoption of more secure chip-enabled credit cards to safeguard consumers from financial fraud and improve confidence in the marketplace. We study the effects of this technological innovation in payment security on household credit outcomes. Using a matched sample staggered difference-in-differences event study, we show that before this intervention fraud exposed consumers faced decline in access to credit. Post this innovation, consumers see greater credit availability. We then examine consumer behavior associated with exposure to fraud and find that consumers reduce their credit demand and face increased financial distress. These findings do not change following the innovation. Heterogeneity analysis shows that low credit score households are more likely to have higher decline in credit demand and increased financial distress. Our findings suggest that persistent consumer distrust underscores the need for further policy innovations, such as one-time passcodes for credit card transactions and sufficient financial education to consumers. In Chapter 3, a joint work with Corbin Fox, we study how the outcomes of public predictions influence user behavior and reputation in online retail investor communities. Using a novel dataset of over 13,000 “Ban Bets” submitted to Reddit’s WallStreetBets, we analyze how users respond after making high-visibility forecasts tied to a self-imposed five-day ban if incorrect. We track engagement (comments), attention (upvotes), and reputation (upvotes per comment) for 14 days before and after each user’s first bet. We find that users who make correct predictions increase their activity and visibility, while incorrect users disengage and suffer reputational losses. Winners receive a short-term boost in reputation (+47%), whereas losers experience a persistent decline (-29%). These dynamics are not driven by selection or moderation but reflect community-level responses to prediction accuracy. Our results show that correctness carries measurable social value in informal financial spaces. Even in meme-driven environments, users are held accountable for public forecasts through peer feedback mechanisms, highlighting the role of informal reputational incentives in shaping participation and influence in digital markets."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Essays on retail trading and credit cards"]}]}],"canonical_facts":{"dc:contributor":["Pennacchi, George","Kahn, Charlie","Kiku, Dana","Xu, Qiping","Fonseca, Julia"],"dc:creator":["Mohr, Justin"],"dc:date":["2025-04-23","2025-05"],"dc:description":["Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01","The student, Justin Mohr, accepted the attached license on 2025-04-22 at 20:37.","The student, Justin Mohr, submitted this Dissertation for approval on 2025-04-22 at 20:57.","This Dissertation was approved for publication on 2025-04-23 at 14:28.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21906 on 2025-10-19 at 19:15:25","My dissertation focuses on retail trading and household finance. The abstracts of the three chapters are as follows: In Chapter 1, I use days on which social media platform connectivity is exogenously interrupted to study social media’s impact on retail trading. It provides evidence consistent with social media platforms spreading fanatical optimism rather than rational beliefs. On “outage” days, social media-discussed stocks experience an increase in retail trading volume concentrated in selling. Social media-discussed stocks experience a price decline that reverses over the subsequent day. These results can be explained by a theoretical model of fanatical optimism and are robust to a battery of alternative explanations. The paper’s findings highlight the important role of social media on retail traders’ belief formation and its stock market consequences. In Chapter 2, a joint work with Divij Kohli, we study credit card fraud. Credit card fraud is the most common type of identity fraud in the U.S. with a cost of over $11.64 billion. In 2014, the U.S. government pushed for widespread adoption of more secure chip-enabled credit cards to safeguard consumers from financial fraud and improve confidence in the marketplace. We study the effects of this technological innovation in payment security on household credit outcomes. Using a matched sample staggered difference-in-differences event study, we show that before this intervention fraud exposed consumers faced decline in access to credit. Post this innovation, consumers see greater credit availability. We then examine consumer behavior associated with exposure to fraud and find that consumers reduce their credit demand and face increased financial distress. These findings do not change following the innovation. Heterogeneity analysis shows that low credit score households are more likely to have higher decline in credit demand and increased financial distress. Our findings suggest that persistent consumer distrust underscores the need for further policy innovations, such as one-time passcodes for credit card transactions and sufficient financial education to consumers. In Chapter 3, a joint work with Corbin Fox, we study how the outcomes of public predictions influence user behavior and reputation in online retail investor communities. Using a novel dataset of over 13,000 “Ban Bets” submitted to Reddit’s WallStreetBets, we analyze how users respond after making high-visibility forecasts tied to a self-imposed five-day ban if incorrect. We track engagement (comments), attention (upvotes), and reputation (upvotes per comment) for 14 days before and after each user’s first bet. We find that users who make correct predictions increase their activity and visibility, while incorrect users disengage and suffer reputational losses. Winners receive a short-term boost in reputation (+47%), whereas losers experience a persistent decline (-29%). These dynamics are not driven by selection or moderation but reflect community-level responses to prediction accuracy. Our results show that correctness carries measurable social value in informal financial spaces. Even in meme-driven environments, users are held accountable for public forecasts through peer feedback mechanisms, highlighting the role of informal reputational incentives in shaping participation and influence in digital markets."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/129561"],"dc:language":["en","eng"],"dc:rights":["© 2025 Justin Mohr"],"dc:subject":["Social media","Investor activity","Information","Influencers","Belief formation","Payment Security","Consumer Credit","Fraud Risk","Credit Card","Lending","Credit Information","Household Finance"],"dc:title":["Essays on retail trading and credit cards"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Finance"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:05Z"}