We discovered that numerous variables comprised various pre-existing codes that were almost certainly the same item. Some constructs were synonyms and were merged into a single phrase (i.e., financial literacy, financial knowledge, investment literacy, and technical financial knowledge were considered jointly as a single construct of financial literacy). Following the grouping process, the pre-existing set of codes was finalized and blended with some newly emerged codes, leading to a final number of 41 codes.
Similar or related codes were grouped into four primary groupings for intention studies, six for behavior studies, and four for decision making studies. Subsequently, we assessed all 14 data groups to confirm the sub-groups. Then, the accuracy of the themes was reassessed in the next stage. We also ensured that all of the developed main themes and sub-themes were appropriate for data representation. As such, the theme of personal factors was divided into two categories during this process, namely psychological and cognitive factors. Finally, the studies had 6 main themes and 17 sub-themes.
In addition to the direct impact of the aforementioned variables on investment intention, a number of studies have revealed the mediating and moderating mechanisms between the variables and intention. Seven studies were related to the stock market, while only one study was related to Sukuk (see
Table 8). In the mediating analysis, two studies concluded that attitude is an effective mediator between previous behavior and intention [
7] and between financial knowledge and investment intention [
8]. Meanwhile, two studies examined perceived risk as a mediator between psychological factors, social factors, and investment decisions [
16] and between brand equity and investment intention [
10]. Three of the five studies that analyzed the moderating role indicated a positive effect of moderating variables, such as the effect of religious aspects on the social influence–intention relationship [
30] and financial self-efficacy (FSE) on the personality traits–intention relationship [
8]. Individuals’ personality and perceptive factors towards stock investment intention were found to be moderated by gender, age, and experience [
9].
3.3.1. Personal Factors
The review revealed that the personal factors could further be divided into two major sub-themes, psychological and cognitive factors. The first sub-theme of psychological factors is attitude. Individual attitudes were associated with investment behavior in 11 of the studies. The majority of the studies applied the TPB as a model, except Sumiati et al. [
21] and Raut et al. [
6], who tested the TRA. Most of the studies highlighted the direct effects of attitude, except Raut [
7], Akhtar and Das [
8], Ashidiqi and Arundina [
27], and Sivaramakrishnan et al. [
12]. Individuals with a positive attitude toward a behavior are more likely to engage in it [
8,
31], while negative attitudes are the result of a set of beliefs from outcomes that are both extremely unfavorable and unlikely [
72]. Consequently, an individual’s attitude toward a particular behavior is a good predictor of their intent to engage in this behavior [
8].
A positive attitude toward investing improves the intention to invest in Shariah-compliant equity mutual funds among Indonesian college students because they believe that doing so will be rewarding, useful, and beneficial [
21]. The findings were consistent with several other studies, where attitude influenced university students’ inclination to invest in a pension fund in Italy [
31] and Sukuk in Indonesia [
27]. Moreover, Raut [
7] also discovered that attitude can also serve as a significant mediating variable between past behavior and intention. Investors frequently conduct a biased search of their memory for previously acquired experiences to support their attitude and influence their intention regarding a current investment decision. The mediating role of attitude between financial knowledge and intention was also evidenced in past studies [
8].
Secondly, PBC, or people’s perception to perform a given behavior, was found to be a positive predictor of investment intention in the stock market [
7,
8,
9,
11], retirement [
31], and Sukuk [
27]. Contrarily, Dewi and Tamara [
28] discovered a negative effect of PBC on the intention but a positive effect on the behavior of employees to invest in retail bond products. However, the findings were questionable, as the theories and previous studies proved that intention has a similar effect to that of behavior. Akhtar and Das [
8], who tested the direct and indirect effects of PBC, also tested FSE to capture PBC and reported that FSE has a significant mediating and moderating effect between personality traits and intention.
Thirdly, moral norms, or one’s perception of the moral correctness or incorrectness of performing a behavior, were added as a new component of TRA by Raut et al. [
6]. Moral norms are defined as one’s own beliefs regarding the obligation to perform or refuse to execute a particular behavior including intrinsic motivation. The authors indicated that it could substantially impact investors’ intentions toward SRI in India. Similarly, Khan et al. [
30] showed that intrinsic motivation carries considerable beneficial effects on investors’ intention to participate in Sukuk.
The next sub-theme, personality traits, represents inherent features of an individual; thus, they may operate as antecedents to perceptual constructs in predicting an individual’s behavioral intention. For instance, a cheerful individual may find stock investment pleasurable [
9,
25]. Meanwhile, risk tolerance is a personality trait that could affect investors’ investment behavior. Lim et al. [
1] studied the differences in investment decisions and behaviors between high- and low-uncertainty-avoidance investors. Based on their study, investors with low uncertainty avoidance demonstrated high risk tolerance and confusion or ambiguity about the success of their investment (i.e., will it yield profit or loss?). On the other hand, individuals with risk tolerance tend to take on investments before fully understanding the financial risks [
73]. This positive high risk tolerance–intention relationship has been evidenced in the stock markets of Saudi Arabia [
5,
14] and Malaysia [
4], with the exception of the unit trust in Malaysia [
23]. According to Akhtar and Das [
8], individuals with a high preference for innovation and risk-taking proclivity are more likely to invest in financial markets, especially when they have a high level of confidence in their ability to do so. As such, Cao et al. [
13] analyzed personality traits such as loss aversion, regret aversion, and mental accounting to establish a substantial impact on investment decision making in Vietnam. Meanwhile, Lai [
9] demonstrated the big five taxonomies, namely openness, extroversion, agreeableness, conscientiousness, and neuroticism, to positively influence stock investment intention.
Of the available literature, only two studies covered the fifth sub-theme, past behavior. Mak and Ip [
20] claimed that individual investors in Mainland China and Hong Kong were driven by experience or an investment assessment process when making investment decisions. Contrarily, Raut [
7] discovered that previous investment experience had no bearing on the investment intentions of Indian stock market investors. However, the relationship between past behavior and investment intention becomes significant when it has been mediated by attitude.
The sixth sub-theme is compatibility. According to Khan et al. [
30], individuals choose and use products or services in line with their lifestyles and beliefs, thus increasing their intention to invest in Sukuk. Since Sukuk is an Islamic financial instrument, Muslims in the Muslim-majority nations, such as Pakistan, believe that it is compatible with their way of life, evidenced by a strong compatibility–investment intention relationship.
Heuristics is the seventh sub-theme. Previous studies indicated that heuristics helps investors to make decisions because it is a strategy that does not consider all information to make a faster, cheaper, and/or more accurate decision compared to a more complicated method [
74]. Representativeness, overconfidence, anchoring, gambling, and availability bias are among the heuristic variables that can positively impact investment decision making [
13,
19]. For instance, heuristics played a significant role in making investment decisions in Vietnam [
13]. The study outcome demonstrated that heuristic biases influence investors to act irrationally and make trading errors. Hence, heuristics can also negatively impact an individual’s investing decisions. Psychologically, investors cannot make better investment decisions due to heuristics.
The final sub-theme under the psychological theme is emotion. Angry investors may be able to obtain more clues about the situation because they are more aware of what is taking place, are more willing to consider other aspects, and have a better understanding of the situation than normal investors. Additionally, fear can also help investors to make smarter investments. Investors who are afraid are more alert to the risks and uncertainties of investment; hence, they would rarely invest in risky or unknown stocks. Fear also allows investors to be more analytical of their decisions. Investors who are in a good mood can make balanced and precise decisions, enabling them to take risks with good outcomes. When in a good mood, they are able to have a realistic and positive view of the situation. Hence, anger, fear, and a positive mood could positively influence investors’ decision making. Meanwhile, stress, social interaction, and herding can impair their decision making. Of the six variables studied, anger was identified to bear the greatest impact on Pakistani investors’ stock market selections [
16].
On the other hand, the second major sub-theme under the personal factors is the cognitive factors related to the individuals’ financial literacy. Financial literacy can be categorized into subjective and objective knowledge [
75,
76]. The term “subjective knowledge” refers to the self-assessed financial confidence (i.e., how each individual perceives their knowledge of finance). Meanwhile, objective knowledge is the fundamental financial knowledge based on an individual’s understanding of finance and economics concepts, such as inflation, stock markets, savings, credit, and insurance. In short, both subjective and objective financial literacy are strong predictors of intention [
4,
6,
7,
22]. However, only objective financial literacy was proven to affect an individual’s investment intentions in the Indian stock market [
8,
12]. The authors claimed that objective financial literacy is the actual knowledge possessed by an individual that enables prospective investors to generate more external-based thoughts in uncertain financial market conditions. Contrarily, Shehata et al. [
5] reported that subjective knowledge has a greater influence than objective knowledge on stock investment intention in Saudi Arabia. Meanwhile, Kaur and Kaushik [
26] added that both subjective and objective financial literacy can positively affect mutual fund investment intention in India. In the context of pension funds among Italian students, Bongini and Cucinelli [
31] discovered that objective financial literacy (money management and pension knowledge) and other TPB predictors are positively associated with their intention to invest.
3.3.2. Social Factors
Previous studies examined social factors in the context of social influence and religiosity. In stock market decision making, investors were influenced by their social influences in Malaysia [
4], Saudi Arabia [
14], India [
7,
8,
12], Pakistan [
16,
17], Vietnam [
13], and Taiwan [
9]. Similarly, social influences were also discovered in Sukuk investments in Pakistan [
30] and Indonesia [
27], and in Islamic mutual funds [
21] and retail bonds [
28] in Indonesia, while not present in retirement planning in Italy [
31]. Khawaja and Alharbi [
14] investigated the impacts of social influence in terms of advocate recommendations, such as advice or recommendations from other stockholders, brokers, friends, and family members, that could significantly affect the investor behavior in the Saudi investment opportunity. However, the image built by the company over time based on its financial practices largely influences investors’ judgments compared to advocated recommendations. Meanwhile, Cao et al. [
13] investigated the social factor in terms of herding behavior. Herding is a situation in which all individuals behave similarly to one another, even if their private information would suggest otherwise, or they are likely to replicate rational or irrational past behavior [
77]. Investors who rely on inaccurate information tend to imitate others’ ideas and decisions. Herding usually affects individual investors, especially those who are incapable of assessing the market due to literacy issues [
13] and private information [
17].
Religious beliefs were strong predictors, especially those related to Shariah-compliant investments, such as in Shariah equity mutual funds [
21] and Sukuk [
27,
29,
30]. Several other studies have also examined the moderating role of religion. Khan et al. [
30] revealed that religion strengthened the relationship between compatibility (suitability with individuals’ actions, lifestyle, and mode of thinking), internal factors (family members, peers, friends, and relatives), external factors (social media), and intrinsic motivation (individuals’ inner satisfaction) toward Sukuk investment intention. The authors also added that Muslims who believe in a system of reward and punishment on Judgment Day are more inclined to invest in Islamic financial instruments or products.
3.3.3. Market Information
Investor behavior is influenced by market variables such as price movements, news from politics and society, forecasts for future trends, information from others, and the importance of stocks [
78]. Market information is also associated with risk aversion. News of an impending economic recession influences risk-averse investors, who lose confidence in selling their stocks. Meanwhile, high-risk investors with extra cash will seize the opportunity to buy stocks at a low price [
79]. Hence, market information is a positive predictor of investment intention in the stock market in Vietnam [
13] and Saudi [
14], unit trust in Malaysia [
23], and Sukuk in the UAE [
29]. Cao [
13] indicated that market-based factors such as price fluctuations, market information, past trends of a stock, fundamentals of underlying stocks, customer choice, and reactions to price changes were identified as positive influences on investors’ behavior. Therefore, it implied that the market feature was highly valued in investment decisions in Vietnam. On the other hand, Khawaja and Alharbi [
14], who investigated investors’ behavior in the Saudi stock market, found that it was influenced by neutral information, including internet information, information about government holders, stock market volatility, recent price swings, and press coverage. The Saudi stock market also considered all accounting information related to the firm, such as a business stock worthiness, financial status, predicted corporate gains, expected dividends, past performance, and the dividend paid.
The decision to invest among investors is influenced by their capacity to collect financial data to analyze and comprehend certain instruments and markets [
23,
29]. The extensive availability of information is the most significant benefit to investors, as it provides them with an advantage over other investors who may lack the necessary information to make a comprehensive decision through market analysis [
23]. However, Duqi and al-Tamimi [
29] found a positive coefficient for information availability and investment in Sukuk, but it was statistically insignificant. The findings show that the availability of information is insufficient from the perspective of investors, implying that UAE investors are aware of the importance of information availability in making investment decisions.
3.3.5. Product-Related Factors
Product-related factors can be grouped into three sub-themes, namely risk and return, brand equity, and product features. The term “return” refers to the benefit/reward that investors receive in the future from their investment. Meanwhile, “risk” refers to the uncertainty surrounding the benefits. Hence, risk and return can be considered as the investment purpose influencing investment intention. Risk and return are positively correlated with Sukuk investments in Indonesia [
27] and the UAE [
29]. The financial performance, which can be measured based on risk and return, was identified to have the greatest impact, followed by subjective norms and attitudes towards SRI intention in the Indian stock market [
6]. Furthermore, investment in environmentally friendly companies is not only influenced by subjective norms and attitudes but is most importantly influenced by the potential future benefits based on their prior financial performance [
6]. However, Annamalah et al. [
23] claimed that mutual fund investment return does not have a significant impact on the investment behavior of Malaysian investors because past returns may not guarantee the current expected return.
Brand equity is embodied through variables such as brand awareness, brand quality, and brand loyalty [
10]. A cross-country study performed in Turkey and Ireland [
10] indicated that brand equity manifests itself through brand awareness, brand quality, and brand loyalty variables. These variables significantly impact investors’ intention to invest. In other words, changes in brand loyalty can impact the stock market investment intention. The findings also revealed a connection between brand equity perceptions and intention to invest, mediated by perceived risk, with a stronger effect in the Turkish and a weaker effect in the Irish stock market. Investors in developing markets were more risk-averse compared to those from developed markets when making investment decisions.
The third sub-theme focused on product features, such as attractiveness, accessibility, liquidity, affordability, and low riskiness [
28,
29]. UAE investors prefer to invest in Islamic Sukuk due to the Sukuk’s features [
29]. Meanwhile, specific product features of mutual funds, including professional management, fractional purchases, lower brokerage, less volatility, diversification, regular income benefits with skilled knowledge, and limited liability with a trustworthy regulatory body, have all influenced investors’ decisions to adopt mutual funds in North India [
24]. Contrarily, product features were not significant in influencing employees’ intentions to invest in retail bonds in Indonesia [
28].