The Value investment and Growth investment are investment strategies of choosing stocks. These two methods are adopted by international financial investment institutions and mutual fund managers. The study is aim to learn when we classify value stock and growth stock by market-to-book ratio and price-earning ratio, if the investment return would be higher than TSEC weighted index. In addition, we seek for a better investment strategy to improve investment performance further. The study also looks into market abnormal effects , such as January effect, size effect¡Ketc, and also discuss about the variables of stocks holding period and debt ratio. The monthly and yearly investment return rates are used to calculate 1, 2, 3, 4, and 5 year accumulated abnormal stock return ratio and evaluate if these variables affect investment performance of value stock and growth stock. The results are as following: 1. When classification of market-to-book ratio are adopted, the investment return of value stock is higher than growth stock. 2. When classification of market-to-book ratio are adopted, the investment return of low debt ratio stock is higher than high debt ratio stock. However, when classification of price-earning ratio are adopted, it is not obvious. 3. When bull market is formed in Taiwan stock market whose index is still low, invest in value stock could get a good long term investment performance. 4. Regarding the evaluation of risk, the vibration of growth stock is more than value stock. The vibration of TSEC weighted index is the least. 5. The January effect exists in Taiwan stock market. However, the size effect is not obvious. 6. TSEC weighted index and the Dow Jones Industrial index affect the investment return of value stock and growth stock; the TSEC weighted index, value stock and growth stock are positively correlated. The Dow Jones Industrial Index, value stock and growth stock are negatively correlated.

Bakgrund:  Börsnoterade bolag strävar efter att maximera aktieägarvärdet genom strategiska beslut som förvärv och avyttringar. Avknoppningar, där en del av företaget blir ett självständigt bolag, har sedan införandet av Lex Asea 1991 blivit en attraktiv strategi i Sverige delvis drivet av skatteförmåner. Internationella studier visar att avknoppningar ofta leder till förbättrad effektivitet och högre värdering. Trots positiva internationella forskningsresultat är avknoppningars effekter på den svenska aktiemarknaden relativt outforskad och resultaten varierande, vilket motiverar en djupare analys. Syfte: Syftet med denna studie är att analysera avknoppningars effekter på aktieavkastningen för bolag på den svenska aktiemarknaden mellan åren 2005–2023.   Metod: En kvantitativ ansats har använts för att genomföra eventstudier som undersöker aktieavkastningen både vid annonseringstillfället och på lång sikt. Studien inkluderar data från olika eventfönster och använder relativ storlek, industriell fokusering och konjunkturläge som förklaringsvariabler för att förstå deras påverkan på den observerade abnormala aktieavkastningen. Statistiska tester, inklusive t-tester och regressioner, används för att säkerställa resultatens trovärdighet.   Slutsats: Resultaten visar en statistiskt signifikant abnormal aktieavkastning vid annonseringen av en avknoppning, vilket tyder på en positiv marknadsreaktion. På lång sikt observeras även viss signifikant abnormal avkastning under specifika eventfönster, vilket indikerar att avknoppningar kan bidra till fortsatt värdeskapande över tid. Marknadsreaktionerna påverkas i varierande grad av faktorer såsom industriell fokusering, relativ storlek och konjunkturläge vid avknoppningstillfället. / Background: Publicly listed companies strive to maximize shareholder value through strategic decisions such as acquisitions and divestitures. Spin-offs, where a part of the company becomes an independent entity, have become an attractive strategy in Sweden since the introduction of Lex Asea in 1991, partly driven by tax benefits. International studies show that spin-offs often lead to improved efficiency and higher valuation. Despite positive international research results, the effects of spin-offs on the Swedish stock market are relatively unexplored and the results are varied, motivating a deeper analysis. Purpose: The purpose of this study is to analyze the effects of spin-offs on stock returns for companies on the Swedish stock market between the years 2005–2023. Method: A quantitative approach has been used to conduct event studies that examine stock returns both at the announcement and in the long term. The study includes data from various event windows and uses relative size, industrial focus, and economic conditions as explanatory variables to understand their impact on the observed abnormal stock returns. Statistical tests, including t-tests and regressions, have been used to ensure the reliability of the results. Conclusion: The results show a statistically significant abnormal stock return at the announcement of a spin-off, indicating a positive market reaction. In the long term, some significant abnormal returns are also observed during specific event windows, suggesting that spin-offs can contribute to continued value creation over time. Market reactions are influenced to varying degrees by factors such as industrial focus, relative size, and economic conditions at the time of the spin-off.