• Management & Information Systems Review
• /
• v.30 no.2
• /
• pp.237-255
• /
• 2011

This empirical study is focused on practical application of Range-Based Volatility which is estimated by opening, high, low, closing price of overall asset. Especially proper forecasting period is what I want to know. There is four useful Range-Based Volatility(RV) such as Parkinson(1980; PK), Garman and Klass(1980; GK) Rogers and Satchell(1991; RS), Yang and Zhang(2008; YZ). So, four RV of KOPSI 200 index during 2000.5.22-2009.9.18 was used for empirical test. The emprirical result as follows. First, the best RV which shows the best forecasting performance is PK volatility among PK, GK, RS, YZ volatility. According to estimating period forcasting performance of RV shows delicate difference. PK has better performance in the period with financial crisis of sub-prime mortgage loan. if not, RS is better. Second, almost result shows better performance on forecasting volatility without sub-prime mortgage loan period. so we can say that forecasting performance is lower when historical volatiltiy is comparatively high. Finally, I find that longer estimating period in AR(1) and MA(1) model can reduce forecasting error. More interesting point is that the result shows rapid decrease form 60 days to 90 days and there is no more after 90 days. So, if we forecast the volatility using Range-Based volaility it is better to estimate with 90 trading period or over 90 days.

• Asia-Pacific Journal of Business
• /
• v.10 no.3
• /
• pp.37-51
• /
• 2019

In this paper, we investigate the performance of anomaly factors in Asia-Pacific Stock market and show the higher Sharpe ratio of the volatility managed smart beta portfolio. The smart beta portfolio combines the benefit of passive strategy and active strategy. However, the smart beta portfolios are seems to be exposed to the risk of anomaly factors from the perspective of traditional financial equilibrium model. Therefore, the smart beta strategy may generate negatively skewed returns unappealing to investors having lower risk tolerance. Our empirical investigations find that the return of the Asia-Pacific region stock market is more volatile than other regions with the lower efficiency ratio. However, the value factor and the momentum factor of Asia-Pacific region both show good performances. More interestingly, we also find that managing the volatility of the momentum factor in Asia-Pacific stock market almost doubles the efficiency ratio.

• Journal of Intelligence and Information Systems
• /
• v.22 no.2
• /
• pp.81-96
• /
• 2016

As the internet has become widespread and easy to access everywhere, it is common for people to search information via online search engines such as Google and Naver in everyday life. Recent studies have used online search volume of specific keyword as a measure of the internet users' attention in order to predict disease outbreaks such as flu and cancer, an unemployment rate, and an index of a nation's economic condition, and etc. For stock traders, web search is also one of major information resources to obtain data about individual stock items. Therefore, search volume of a stock item can reflect the amount of investors' attention on it. The investor attention has been regarded as a crucial factor influencing on stock price but it has been measured by indirect proxies such as market capitalization, trading volume, advertising expense, and etc. It has been theoretically and empirically proved that an increase of investors' attention on a stock item brings temporary increase of the stock price and the price recovers in the long run. Recent development of internet environment enables to measure the investor attention directly by the internet search volume of individual stock item, which has been used to show the attention-induced price pressure. Previous studies focus mainly on Dow Jones and NASDAQ market in the United States. In this paper, we investigate the relationship between the individual investors' attention measured by the internet search volumes and stock price changes of individual stock items in the KOSDAQ market in Korea, where the proportion of the trades by individual investors are about 90% of the total. In addition, we examine the difference between industries in the influence of investors' attention on stock return. The internet search volume of stocks were gathered from "Naver Trend" service weekly between January 2007 and June 2015. The regression model with the error term with AR(1) covariance structure is used to analyze the data since the weekly prices in a stock item are systematically correlated. The market capitalization, trading volume, the increment of trading volume, and the month in which each trade occurs are included in the model as control variables. The fitted model shows that an abnormal increase of search volume of a stock item has a positive influence on the stock return and the amount of the influence varies among the industry. The stock items in IT software, construction, and distribution industries have shown to be more influenced by the abnormally large internet search volume than the average across the industries. On the other hand, the stock items in IT hardware, manufacturing, entertainment, finance, and communication industries are less influenced by the abnormal search volume than the average. In order to verify price pressure caused by investors' attention in KOSDAQ, the stock return of the current week is modelled using the abnormal search volume observed one to four weeks ahead. On average, the abnormally large increment of the search volume increased the stock return of the current week and one week later, and it decreased the stock return in two and three weeks later. There is no significant relationship with the stock return after 4 weeks. This relationship differs among the industries. An abnormal search volume brings particularly severe price reversal on the stocks in the IT software industry, which are often to be targets of irrational investments by individual investors. An abnormal search volume caused less severe price reversal on the stocks in the manufacturing and IT hardware industries than on average across the industries. The price reversal was not observed in the communication, finance, entertainment, and transportation industries, which are known to be influenced largely by macro-economic factors such as oil price and currency exchange rate. The result of this study can be utilized to construct an intelligent trading system based on the big data gathered from web search engines, social network services, and internet communities. Particularly, the difference of price reversal effect between industries may provide useful information to make a portfolio and build an investment strategy.

• The Korean Journal of Applied Statistics
• /
• v.22 no.2
• /
• pp.261-270
• /
• 2009

Current financial crisis triggered by shaky U.S. banking system adds to the emphasis on the importance of the volatility in controlling and understanding financial time series data. The ARCH and GARCH models have been useful in analyzing economic time series volatilities. In particular, multivariate GARCH(MGARCH, for short) provides both volatilities and conditional correlations between several time series and these are in turn applied to computations of hedge-ratio and VaR. In this short article, we try to assess various MGARCH models with respect to the back-testing performances in VaR study. To this end, 14 korean stock prices are analyzed and it is found that MGARCH outperforms rolling window, and BEKK and CCC are relatively conservative in back-testing performance.

• The Korean Journal of Financial Management
• /
• v.23 no.1
• /
• pp.243-266
• /
• 2006

This paper tests cross hedging performance of the KOSPI 200 stock index futures to hedge the downside risk of the KOSPI, KOSPI 200 and KOSDAQ50 spot market. For this purpose we introduce the minimum variance hedge model, bivariate GARCH(1,1) and EGARCH(1,1) model as hedge models. The main results are as follows; First, we find that the direct hedge performance of KOSPI 200 index futures is better than those of indirect hedge performance. second, in case or cross hedge performance the hedge effect of KOSPI 200 stock index futures market against KOSPI 200 stock index spot market is relatively better than those of KOSPI 200 index futures against KOSPI and KOSDAQ spot position. Third, for the out-sample, hedging effectiveness of the risk-minimization with constant hedge ratios is higher than those of the time varying bivariate GARCH(1,1) and EGARCH(1,1) model. In conclusion, investors are encouraged to use simple risk-minimization model rather than the time varying hedge models like GARCH and EGARCH model to hedge the position of the Korean stock index cash markets.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.380-380
• /
• 2020

가뭄 피해 극복을 위한 인공 함양지 통합관리시스템의 일부로써 지표수-지하수 연계 특성 분석용 의사결정을 전달하는 인공지능 스마트 계측기의 필요성이 꾸준히 제기되어 왔으나 실용성과 효율성을 동시에 갖춘 계측기는 시장에 출시되지 않았다. 기존의 계측기는 단순 측정이 목적이었으며 분석을 위해서는 일정 기간 직접 계측하여 분석하거나, 계측데이터를 원격 망을 통하여 서버로 전송하고 관리자가 데이터를 해석하는 방식을 취하였다. 또한, 수질 계측과 수질의 미소 변동성을 동시에 계측하여 수질 변화상태를 판단 할 수 있는 수질 계측기는 상품화되지 않아 다목적 수질 분석에 한계점을 갖고 있다. 이러한 한계점이 기존의 지하수 수질 계측기로는 불가능한 수중 라돈을 채수 없이 계측 가능하도록 하고, 순간 수질 변화 및 수질 변화 요인분석이 가능한 계측을 위하여 라돈, 전도도, 수위, 수온 및 필름형 pH 센서를 개발하여 적용한 다항목 계측기로 통합하는 연구가 필요한 이유이다. 개발한 계측기는 빅데이터 기반의 지능형 수질 변동성 분석 알고리즘을 내장하고 수직 깊이 방향의 다중심도 계측이 가능하도록 핵심적인 통신 연결성을 확보하였고 다양한 수질에서 견딜 수 있으며 특히 인공함양에서 발생하는 철, 망간에 부식되지 않는 재질을 이용하여 설계한 '지표수-지하수 연계 특성 분석용 다심도 및 인공지능 스마트 계측장치'이다. 본 장치는 기존 지하수 수질 계측기에서는 불가능하였던 순간 수위변화 및 수위변화 요인분석이 가능한 계측을 위하여 초당 측정 샘플링 주파수(10Hz)를 높인 계측회로를 개발하여 적용하였다.

• The Korean Journal of Financial Studies
• /
• v.12 no.1
• /
• pp.163-182
• /
• 2006

본 연구는 장기투자자인 생명보험사 및 연기금의 투자다변화 일환으로 장기투자의 성격에 부합하고 안정적이며 높은 수익이 기대되는 대체투자 중 사회간접자본 자산에 대한 투자방안을 연구목적으로 하여 다음의 분석결과를 도출하였다. 첫째, 생명보험사와 연기금의 금융부문 수익률과 사회간접자본 투자수익률을 비교한 결과 사회간접자본 투자는 변동성이 큰 주식에 비하여 위험은 낮고 안전자산인 채권에 비해서는 상대적으로 높은 수익률을 나타내었다. 둘째, 생명보험사 및 연기금이 사회간접자본 투자에 참여할 경우 사회간접자본 투자에 대한 정부의 수입보장 및 국내 인프라 사업의 사업수익률 수준과 타기관의 목표수익률 등을 종합적으로 고려할 때 15% 수준의 투자수익률이 적합할 것으로 보인다. 다만 최근 국내 주요 사회간접자본 사업의 투자수익률을 볼 때 국가관리사업과 자체관리사업 모두 투자수익률이 낮아지고 있는 추세이므로 장기적으로 이러한 추세를 반영하여 목표수익률의 재조정이 필요한 것으로 보인다. 셋째, 현실적인 간접투자상품의 한계 및 직접투자시의 비용절감효과 등으로 대규모투자자의 경우 전문성을 확보하여 직접투자방식의 참여를 고려할 수 있으며 중소규모투자자의 경우 시장상황 및 위험을 고려하여 펀드를 조성하여 투자하는 것을 고려할 수 있다. 그리고 중장기적으로는 세계적인 추세에 따라 국내 사회간접자본 간접투자 시장이 활성화되고 규모가 커지게 될 것으로 예상되는 바, 간접투자방식을 적극적으로 검토하여야 할 것이다.

• The Korean Journal of Financial Management
• /
• v.13 no.1
• /
• pp.1-49
• /
• 1996

금융정책(金融政策)과 자본시장(資本市場)의 증권가격(證券價格)과의 동태적(動態的) 관련성(關聯性)을 실증적으로 분석한 결과, 동태적(動態的) 구조면(構造面)에서 볼 때 특히 주식시장은 화폐에 대하여 시차를 갖는 반면, 장기채시장과 단기무위험시장에서는 시차를 갖지 않음이 발견되었다. 그리고 증권가격형성 메카니즘을 살펴본 결과, 화폐(貨幣)의 증가(增加)는 부(富)의 효과(效果)로 이어지고 그 결과 주가의 상승이 초래된다. 다른 한편으로 화폐의 증가가 대체효과를 반드시 유발시키지는 않으며, 그 이유로는 투자자들이 장기채를 선호함으로써 가격의 상승을 불러일으키는 반면 무위험자산의 경우 가격의 변동은 일어나지 않았기 때문이다. 끝으로, 가격효과(價格效果)의 존속은 비교적 단기로 끝남이 확인되었다. 증권시장(證券市場)의 장기적(長期的) 구조(構造)를 파악하기 위하여 공적분(共積分) 검정(檢定)을 실시하였다. 단위근(單位根) 검정(檢定)에 의하여 우리나라의 금융시계열은 단위근이 존재한다는 사실이 입증되었다. 따라서 금융시계열이 비정상적(非定常的) 확률과정(確率過程)을 따르고 있다. 공적분(共積分) 검정(檢定)에 의하여 화폐의 실질대수 유통속도와 실질주가, 장단기수익비율, 화폐차등수익률과 소득변화율 사이에는 차분후에 장기적 정상균형관계가 형성되고 있음이 발견되었다. 통화정책과 주가는 장기의 동태적 구조 측면에서 파악할 때 장기정상관계를 유지하고 있다. 그리고 주가는 시차(時差)가 0인 동시적(同時的) 통화정책(通貨政策)과 제1계 시차통화정책과 소득에 의하여 결정되고 있다. 다른 금융시계열은 주가결정에 영향을 미치고 있지 못한 실정이다. 주가의 상승은 부(富)의 효과(效果)와 대체효과(代替效果)를 유발하고 있다. 따라서 통화당국은 이점을 고려하여 화폐정책(貨幣政策)을 수립하여야 한다. 그리고 통화량은 주가의 가격형성에 양(陽)의 효과(效果)를 형성하고 있다. 따라서 화폐의 공급량의 증가는 명목주가(名目株價)의 상승을 유발하고 이에 따라 부(富)의 효과(效果)와 대체효과(代替效果)가 발생한다. 이와 같은 현상의 발견은 정부당국의 통화정책과 자본시장정책에 중요한 의의를 갖고 있다고 하겠다. 주가형성(株價形成)에 대한 통화정책의 효과는 당기 뿐만 아니라 차기에도 이어지고 화폐량과 소득이 주가의 결정에 영향을 미치고 있으며 다른 금융변수(金融變數)들은 영향을 미치지 않고 있다. 그러나 실질화폐잔고와 실질주가 장단기수익비율 화폐차등수익률과 소득변화률과는 장기적(長期的) 정상적(定常的) 균형관계(均衡關係)를 형성하고 있다. 따라서 장기적 관점에서 증권시장은 경제성장을 위한 통화정책과 각 분야의 균형적 성장을 유발할 수 있는 재정정책(財政政策)이 요청되고 있다. 위의 논의에서 유추할 수 있는 것은 화폐의 영향을 완화시키기 위하여 option시장의 개발과 농산물, 광물, 기타 실물 및 금융에 대한 선물시장의 개설이 요청된다. 이와 같은 시장을 통하여 통화 정책이 증권시장에 미치는 과도한 효과를 축소시켜 합리적이고 건전한 증권시장(證券市場)의 발전(發展)과 금융시장(金融市場)의 원활한 발전이 이룩될 수 있을 것이다. 자본시장이론(資本市場理論)에서는 화폐는 무시하고 실물적인 관점에서 증권가격의 결정을 연구하거나 위험분석에 주안점이 주어져 왔었다. 본 연구를 통하여 통화정책의 결과가 자본시장에 직접적으로 영향을 미치고 있음을 확인하였다. 통화금융정책과 주가의 유기적 관계를 확인한 본 논문의 결과를 정책당국이 참고하여 통화금융정책(通貨金融政策) 효율성(效率性)을 극대화(極大化)할 수 있을 것으로 본다.

• Journal of Intelligence and Information Systems
• /
• v.21 no.3
• /
• pp.117-129
• /
• 2015

As the Internet becomes ubiquitous, a large volume of information is posted on the Internet with exponential growth every day. Accordingly, it is not unusual that investors in stock markets gather and compile firm-specific or market-wide information through online searches. Importantly, it becomes easier for investors to acquire value-relevant information for their investment decision with the help of powerful search tools on the Internet. Our study examines whether or not the Internet helps investors assess a firm's value better by using firm-level data over long periods spanning from January 2004 to December 2013. To this end, we construct weekly-based search volume for information technology (IT) services firms on the Internet. We limit our focus to IT firms since they are often equipped with intangible assets and relatively less recognized to the public which makes them hard-to measure. To obtain the information on those firms, investors are more likely to consult the Internet and use the information to appreciate the firms more accurately and eventually improve their investment decisions. Prior studies have shown that changes in search volumes can reflect the various aspects of the complex human behaviors and forecast near-term values of economic indicators, including automobile sales, unemployment claims, and etc. Moreover, search volume of firm names or stock ticker symbols has been used as a direct proxy of individual investors' attention in financial markets since, different from indirect measures such as turnover and extreme returns, they can reveal and quantify the interest of investors in an objective way. Following this line of research, this study aims to gauge whether the information retrieved from the Internet is value relevant in assessing a firm. We also use search volume for analysis but, distinguished from prior studies, explore its impact on return comovements with market returns. Given that a firm's returns tend to comove with market returns excessively when investors are less informed about the firm, we empirically test the value of information by examining the association between Internet searches and the extent to which a firm's returns comove. Our results show that Internet searches are negatively associated with return comovements as expected. When sample is split by the size of firms, the impact of Internet searches on return comovements is shown to be greater for large firms than small ones. Interestingly, we find a greater impact of Internet searches on return comovements for years from 2009 to 2013 than earlier years possibly due to more aggressive and informative exploit of Internet searches in obtaining financial information. We also complement our analyses by examining the association between return volatility and Internet search volumes. If Internet searches capture investors' attention associated with a change in firm-specific fundamentals such as new product releases, stock splits and so on, a firm's return volatility is likely to increase while search results can provide value-relevant information to investors. Our results suggest that in general, an increase in the volume of Internet searches is not positively associated with return volatility. However, we find a positive association between Internet searches and return volatility when the sample is limited to larger firms. A stronger result from larger firms implies that investors still pay less attention to the information obtained from Internet searches for small firms while the information is value relevant in assessing stock values. However, we do find any systematic differences in the magnitude of Internet searches impact on return volatility by time periods. Taken together, our results shed new light on the value of information searched from the Internet in assessing stock values. Given the informational role of the Internet in stock markets, we believe the results would guide investors to exploit Internet search tools to be better informed, as a result improving their investment decisions.

• The Korean Journal of Financial Management
• /
• v.24 no.2
• /
• pp.41-79
• /
• 2007

This study examines the expiration-day effects of stock index futures and options in the Korean stock market. The so-called 'expiration-day effects', which are the abnormal stock price movements on derivatives expiration days, arise mainly from cash settlement. Index arbitragers have to bear the risk of their positions unless they liquidate their index stocks on the expiration day. If many arbitragers execute large buy or sell orders on the expiration day, abnormal trading volumes are likely to be observed. If a lot of arbitragers unwind positions in the same direction, temporary trading imbalances induce abnormal stock market volatility. By contrast, if some information arrives at market, the abnormal trading activity must be considered a normal process of price discovery. Stoll and Whaley(1987) investigated the aggregate price and volume effects of the S&P 500 index on the expiration day. In a related study, Stoll and Whaley(1990) found a similarity between the price behavior of stocks that are subject to program trading and of the stocks that are not. Thus far, there have been few studies about the expiration-day effects in the Korean stock market. While previous Korean studies use the KOSPI 200 index data, we analyze the price and trading volume behavior of individual stocks as well as the index. Analyzing individual stocks is important for two reasons. First, stock index is a market average. Consequently, it cannot reflect the behavior of many individual stocks. For example, if the expiration-day effects are mainly related to a specific group, it cannot be said that the expiration of derivatives itself destabilizes the stock market. Analyzing individual stocks enables us to investigate the scope of the expiration-day effects. Second, we can find the relationship between the firm characteristics and the expiration-day effects. For example, if the expiration-day effects exist in large stocks not belonging to the KOSPI 200 index, program trading may not be related to the expiration-day effects. The examination of individual stocks has led us to the cause of the expiration-day effects. Using the intraday data during the period May 3, 1996 through December 30, 2003, we first examine the price and volume effects of the KOSPI 200 and NON-KOSPI 200 index following the Stoll and Whaley(1987) methodology. We calculate the NON-KOSPI 200 index by using the returns and market capitalization of the KOSPI and KOSPI 200 index. In individual stocks, we divide KOSPI 200 stocks by size into three groups and match NON-KOSPI 200 stocks with KOSPI 200 stocks having the closest firm characteristics. We compare KOSPI 200 stocks with NON-KOSPI 200 stocks. To test whether the expiration-day effects are related to order imbalances or new information, we check price reversals on the next day. Finally, we perform a cross-sectional regression analysis to elaborate on the impact of the firm characteristics on price reversals. The main results seem to support the expiration-day effects, especially on stock index futures expiration days. The price behavior of stocks that are subject to program trading is shown to have price effects, abnormal return volatility, and large volumes during the last half hour of trading on the expiration day. Return reversals are also found in the KOSPI 200 index and stocks. However, there is no evidence of abnormal trading volume, or price reversals in the NON-KOSPI 200 index and stocks. The expiration-day effects are proportional to the size of stocks and the nearness to the settlement time. Since program trading is often said to be concentrated in high capitalization stocks, these results imply that the expiration-day effects seem to be associated with program trading and the settlement price determination procedure. In summary, the expiration-day effects in the Korean stock market do not exist in all stocks, but in large capitalization stocks belonging to the KOSPI 200 index. Additionally, the expiration-day effects in the Korean stock market are generally due, not to information, but to trading imbalances.