Judul: SRI-KEHATI Index Investor Response to the Determination of the Status of the COVID-19 Pandemic in Indonesia
Abstrak: Penetapan COVID-19 sebagai pandemi di Indonesia melalui Keputusan Presiden Nomor 11 tahun 2020 tentang Penetapan Kedaruratan Kesehatan Masyarakat Coronavirus Disease 2019 berpotensi menghasilkan reaksi pasar terutama pada indeks SRI-KEHATI yang dinilai relatif lebih stabil dan diharapkan mampu bertahan pada kondisi sulit. Penelitian dilakukan untuk mengetahui apakah indeks SRI-KEHATI dapat digolongkan berkinerja baik pada kondisi tidak normal selama pandemi COVID-19. Penelitian menggunakan metode event study dengan metode penarikan sampel purposive sampling diukur dengan rentang waktu 5 hari sebelum dan 5 hari sesudah peristiwa serta 120 hari periode estimasi. Teknik analisis data menggunakan uji normalitas Shapiro-Wilk uji beda dengan pendekatan Paired Sample T-test dan Wilcoxon Signed rank test dengan peranti lunak SPSS 25. Hasil dari penelitian ini menunjukan bahwa penetapan pandemi COVID-19 di Indonesia tidak memberikan reaksi yang signifikan pada abnormal return dan trading volume activity pada perusahaan yang terdaftar dalam Indeks SRI-KEHATI di Bursa Efek Indonesia., The Declaration of COVID-19 as a pandemic in Indonesia through Presidential Decree No. 11 of 2020 on the Declaration of a Public Health Emergency for Coronavirus Disease 2019 had the potential to trigger market reactions, particularly on the SRI-KEHATI index, which was considered relatively stable and expected to withstand challenging conditions. This research was conducted to determine whether the SRI-KEHATI index could be classified as performing well during abnormal conditions amid the COVID-19 pandemic. The study utilized the event study method with purposive sampling, measured within a 5-day window before and after the event, and a 120-day estimation period. Data analysis employed the Shapiro-Wilk test for normality, paired sample T-test, and Wilcoxon signed-rank test using SPSS 25 software. The findings of this study indicated that the declaration of the COVID-19 pandemic in Indonesia did not significantly affect abnormal return and trading volume activity for companies listed in the SRI-KEHATI Index on the Indonesia Stock Exchange.
Keyword: abnormal return, trading volume activity, event study, SRI-KEHATI

Judul: Analysis of Investor Reactions to the Announcement of Right Issue At The Indonesian Stock Exchage Issuers Before And During The Covid-19 Pandemic
Abstrak: Pandemi COVID-19 berdampak terjadinya fluktuasi terhadap pergerakan harga saham, dan sangat mempengaruhi kondisi ekonomi begitupun reaksi investor terhadap kebijakan right issue yang akan mempengaruhi minat jual beli saham. Studi ini mengamati perkembangan aktivitas pasar di mana investor bereaksi terhadap informasi dengan mempertimbangkan sifat dinamis pasar modal melalui bullish dan bearish sebelum maupun selama pandemi COVID-19. Penelitian ini bertujuan untuk mengidentifikasi periode bullish dan bearish di Bursa Efek Indonesia periode 2017-2020, mengidentifikasi pengaruh COVID-19 terhadap aksi right issue, menganalisis perbedaan rata-rata excess return dan likuiditas saham yang diukur dengan bid-ask spread sebelum dan sesudah pengumuman right issue masa sebelum dan selama pandemi COVID-19, kemudian menganalisis pengaruh right issue pada dividen per share yang akan diterima oleh pemegang saham masa sebelum dan selama pandemi COVID-19, serta menguji apakah pasar modal Indonesia mengikuti the semi strong efficient market. Penelitian ini menggunakan 50 sampel perusahaan dari tahun 2017-2020, metode penarikan sampel menggunakan purposive sampling dan menggunakan event study dengan pendekatan market model, uji normalitasnya adalah Kolmogorov–smirnov, uji statistik menggunakan uji beda dua rata (wilcoxon signed rank test dan paired sample t- test), serta identifikasi bullish dan bearish menggunakan analisis candlestick. Secara umum IHSG menunjukkan pola bullish sebagai tren utama dengan persentase (64.58%) dan bearish (35.42%). Hasil penelitian menunjukkan bahwa terdapat perbedaan excess return yang signifikan sebelum dan sesudah pengumuman rights issue pada periode sebelum COVID-19 namun tidak terdapat perbedaan excess return selama pandemi COVID-19. Sedangkan hasil penelitian menunjukkan bahwa tidak terdapat perbedaan likuiditas saham sebelum dan sesudah pengumuman rights issue, baik sebelum maupun selama pandemi COVID-19. Begitupun hasil pengujian dividen terdapat perbedaan DPS sebelum dan sesudah pengumuman right issue sebelum COVID-19 yang ditunjukkan dengan perbedaan jumlah rata-rata DPS sebelum dan sesudah right issue, sementara DPS saat COVID-19 tidak terdapat perbedaan yang signifikan, membuktikan bahwa adanya pengaruh pandemi yang menyebabkan perlambatan ekonomi berdampak terhadap pasar modal, sehingga kegiatan penawaran terbatas yang dilakukan perusahaan dengan menerbitkan right issue menyebabkan jumlah lembar saham yang beredar meningkat namun laba yang diperoleh perusahaan tidak mengalami peningkatan. Hasil empiris menunjukkan bahwa pasar modal Indonesia mengikuti bentuk semi strong dari efisiensi pasar., The COVID-19 pandemic has the impact of fluctuations on stock price movements, and greatly affects economic conditions as well as investors' reactions to rights issue policies which will affect the interest in buying and selling shares. A study of the development of market activity in which investors react to information taking into account the dynamic nature of the market through bulls and bears before and during the COVID-19 pandemic. This study aims to identify the bullish and bearish periods on the Indonesia Stock Exchange for the 2017-2020 period, the influence of the influence of COVID-19 on the rights issue, to analyze the difference in average excess return and stock liquidity as measured by the bid-ask spread before and after the announcement of rights. the issue of the period before and during the COVID-19 pandemic, then analyze the effect of the right issue on dividends per share that will be received by shareholders before and during the COVID-19 pandemic, as well as whether the Indonesian capital market follows a semi-strong efficient market.
Keyword: Bullish, Bearish, Bid-Ask Spread, COVID-19, Excess Return, Semi Strong From

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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