The role of celebrities in influencing consumer behavior has been extensively explored across marketing literature ([12]; [28]). Celebrity endorsements have been shown to enhance brand recall, shift consumer attitudes, and increase purchase intentions ([35]; [1]). In the sports context, athletes often serve as both product and brand, with their popularity and marketability closely tied to merchandise sales ([13]; [8]).

However, the impact of non-sport celebrities on sports-related consumption remains an underexplored area. Studies on cross-category celebrity influence suggest that public relationships can serve as informal endorsements, transferring brand equity from one domain to another ([24]; [33]). Theories such as parasocial interaction ([19]) and celebrity worship ([26]) offer psychological frameworks for understanding how fans’ emotional investment in celebrities can shape their consumer behaviors

Swift’s cultural capital—characterized by her loyal fanbase and strategic brand alignments—has previously impacted industries including fashion, tourism, and streaming platforms ([27]; [23]). The NFL, traditionally male-dominated, represents a novel arena for such influence. The alignment of Swift’s cultural persona with Kelce’s athletic identity creates a hybrid brand narrative with the potential to attract new consumers and redefine fandom ([4]).

While previous cases such as David Beckham and Victoria Beckham ([37]), or Tom Brady and Gisele Bündchen ([6]), hinted at the power of celebrity pairings, empirical research quantifying these effects on merchandise sales is sparse. This study contributes to this gap by using a real-time natural experiment to assess measurable outcomes.

Parasocial Interaction Theory (PIT), first introduced by [19], describes the illusion of a face-to-face relationship between media consumers and performers. These one-sided interactions, though lacking mutual awareness, can foster strong emotional connections that mimic real-life social bonds. Viewers may come to feel as though they “know” the celebrity, generating loyalty and attentiveness akin to interpersonal relationships.

In the decades since its inception, PIT has been widely applied across media and marketing disciplines to explain how audiences engage with television personalities, influencers, and celebrities ([15]; [11]). Parasocial relationships (PSRs) often lead to increased trust, perceived intimacy, and behavioral outcomes such as following endorsements, defending public figures, or mimicking consumption patterns ([14]; [36]).

Applied to the context of Taylor Swift and Travis Kelce, PIT suggests that Swift’s fans—many of whom have long-standing parasocial attachments to her—may transfer those emotional bonds to products and symbols associated with her personal life. This includes NFL merchandise tied to Kelce, whose jersey sales surged following Swift’s public support. Because PSRs involve perceived relational investment, Swift’s endorsement of Kelce through public appearances can act as an implicit cue, guiding consumer preferences and identity formation, particularly among new or non-traditional NFL audiences ([7]; [17]).

Thus, PIT informs the hypothesis that Swift’s association with Kelce influenced not only media attention but also consumer identity and behavior, as fans enacted loyalty and affiliation through tangible purchases like jerseys—effectively blending entertainment fandom with sports consumerism.

Celebrity Endorsement Theory (CET), as conceptualized by [28], frames celebrity endorsement as a symbolic transfer of meaning. Celebrities carry cultural meanings—such as status, style, values, or charisma—that can be transferred to products and brands they are associated with. This process occurs through a three-stage movement model: from the celebrity to the product, and then from the product to the consumer. Unlike traditional advertising rooted in product features, CET emphasizes symbolic association and identity signaling.

Research consistently supports the idea that celebrities influence consumer perceptions, attitudes, and purchasing behavior when the perceived fit between the celebrity and the endorsed object is strong ([22]; [1]). The endorsement effect extends beyond commercial campaigns to informal associations; even unsanctioned or organic connections between a celebrity and a brand can generate similar effects ([24]; [20]).

Taylor Swift’s public appearances at NFL games and her romantic connection to Travis Kelce function as a de facto endorsement of Kelce and, by extension, the NFL. CET suggests that Swift’s personal brand—marked by authenticity, emotional resonance, and cultural relevance—is symbolically transferred to the associated merchandise (e.g., Kelce jerseys), increasing its desirability. Consumers—particularly Swift’s fanbase—may then purchase these items not just to support Kelce or the Chiefs, but as a form of self-expression or affiliation with Swift’s values and lifestyle ([10]).

Thus, CET informs the hypothesis that Swift’s relationship with Kelce contributed not only to media visibility but to shifts in consumer identity and behavior, as fans adopted NFL merchandise as a symbolic extension of their loyalty to Swift’s brand persona.

Consumer Culture Theory (CCT), articulated by [3], offers a framework for understanding consumption as a cultural and identity-based practice, rather than merely a rational or utilitarian one. CCT explores how consumers use goods, brands, and experiences to construct and express their identities, engage with social groups, and navigate symbolic meanings in a marketplace shaped by culture. It situates consumption within broader sociocultural narratives, emphasizing the co-creation of meaning between consumers and brands.

CCT posits that products and brand affiliations become vehicles for self-expression, especially when embedded within shared cultural contexts or emotionally resonant narratives ([34]). This theory is particularly relevant to celebrity-related consumption, where fans adopt material symbols associated with public figures to align themselves with a broader cultural lifestyle or value system ([18]; [31]).

In the case of Taylor Swift’s association with Travis Kelce, CCT helps explain why Swift’s fans may have purchased Kelce or Kansas City Chiefs merchandise. These items became more than sports memorabilia—they transformed into cultural artifacts representing affiliation with Swift’s identity narrative. Her fans (“Swifties”) often engage in identity-signaling consumption aligned with her persona, and the adoption of Kelce jerseys represents an extension of that cultural affiliation ([29]).

Thus, CCT informs the hypothesis that Swift’s association with Kelce catalyzed not just media attention, but identity-driven consumer behavior, as individuals used merchandise purchases to locate themselves within the larger cultural phenomenon of “Swift-Kelce”—a hybridization of pop culture and sport.

Sales Data: Weekly jersey sales rankings from Fanatics (NFL’s official e-commerce partner) from July 1, 2023, to February 29, 2024. Because Fanatics provides weekly sales rankings rather than unit-level sales volume, the dependent variable is a rank-normalized index constructed using a percentile transformation (0 - 100). This approach treats ranks as quasi-continuous while avoiding inappropriate linearity assumptions. The reported “400% increase” reflects the change in Kelce’s rank-index score from Week t − 1 to Week t, not literal sales volume. Media Mentions: Volume of news stories from LexisNexis and Meltwater containing “Taylor Swift” and “Travis Kelce”.Social Media Metrics: Twitter/X engagement data, TikTok trends, and Instagram hashtags.Search Trends: Google Trends data for keywords “Travis Kelce,” “Taylor Swift,” and “Kelce jersey.”

Three major media events were pre-defined prior to analysis:

1) Swift’s first game appearance (Sept. 24)

2) First joint SNL appearance (Oct. 14)

3) Chiefs-Bills playoff game with high-profile coverage (Jan. 21)

These events are modeled as separate interruptions using an event study specification with ±2 week distributed lags.

Intervention Point: September 24, 2023, the date of Swift’s first appearance at a Chiefs game.

Control Variables:

Chiefs’ win-loss recordNFL promotional periods (e.g., playoffs, holiday sales)Player performance statistics (yards, touchdowns)

To strengthen attribution, three comparison series are included:

1) Patrick Mahomes’ weekly jersey rank,

2) George Kittle’s weekly jersey rank (matched tight end), and

3) a league-wide Top 10 jersey index.

To account for potential confounding factors, week of season fixed effects were incorporated to adjust for recurring seasonal patterns in NFL merchandise demand. Indicator variables were included for league wide promotional periods such as Black Friday and the playoff window. As a robustness check, the ITS models were re-estimated with all promotional weeks excluded; the direction and magnitude of the estimated effects remained consistent across specifications.

ITS regression was conducted using Newey-West standard errors to correct for autocorrelation and heteroskedasticity. Correlation analyses were used to assess temporal alignment between media metrics and sales rankings. The following segmented regression model is estimated:

where Y t is the rank-normalized jersey index, Time is a weekly counter, Post is an indicator for weeks after September 24, 2023, and the interaction term captures slope change. The dataset includes 12 pre-intervention weeks and 22 post-intervention weeks. Newey-West lag length was selected using the Bartlett kernel with automatic bandwidth selection ([2]). Ljung-Box tests were applied to evaluate autocorrelation, and Bai-Perron tests were used to identify structural breaks. A controlled ITS/difference in differences model is estimated:

where i indexes players/series and δ_t are week fixed effects.

Qualitative Component: Sentiment analysis of fan discourse on Reddit and TikTok was performed to assess consumer narratives surrounding the Swift-Kelce relationship. Qualitative data were collected from Reddit (r/TaylorSwift, r/NFL, r/KansasCityChiefs), TikTok videos using #KelceSwift and #NFLforSwifties, and Instagram posts tagged with #TaylorSwift and #TravisKelce. The sampling window spanned July 2023 to February 2024. Posts were included if they referenced Swift, Kelce, or NFL merchandise. Sentiment analysis was conducted using VADER, with manual validation on a 10% subsample (κ = .82). The coding process followed a structured protocol to identify themes related to consumer identity, parasocial attachment, and merchandise motivations.