國內共同基金發行檔數持續增加，基金也成為投資人常用投資工具之一，投資組合的管理技術，也在共同基金市場持續成長下而持續增長。國內外長期對於基金決策的研究也相當的豐富，主要研究發現經理人對基金持股數決定是投資決策的重要面向之一。然而，究竟基金持股應該分散或集中，或是”雞蛋是否該放在同個籃子”，投資組合相關文獻一直有著不同的看法，但可以確定的是分散與集中的投資策略各有其優缺點，而其取捨的關鍵在於投資分散雖有風險下降的好處，但同時也可能隱含著更高的監控成本，同時並影響基金績效。
從基金管理的實務角度出發，管理基金需要更多的研究資源，持股多寡將直接反映於基金績效。本研究企圖透過每季公布之基金持股資訊，並驗證其對國內股票型基金之績效影響，希望對投資經理人做為投資決策能更有幫助，藉由有效的控制持股數進而提高基金績效。
實證結果顯示：
1.基金持股對基金績效具有影響，基金經理人採取集中之投資策略，可以降低資訊成本，進而創造較佳績效。
2.無論市場多空頭，基金持股集中因監控成本下降而對基金績效有正面影響。
3.無論基金規模大小，基金持股因監控成本下降對基金績效有正面影響。

As the financial market in Taiwan evolves, mutual funds have become one of the most popular investment tools, and the technique of investment is improving, too. There are many studies in mutual funds, and the discussion on optimum volume of holdings is an important issue.
Should we “put all eggs in one basket or in different baskets?” It is not a easy question to answer. Holding focus in limited stocks has the advantage of performance if you make the right choices. On the other side, holding various has the advantage of risk separation. But holding various will also spend more monitor cost and will offset the performance obviously.
Investments need a larger base of research sources, and it will reflect in performance. This research tries using quarterly fund holdings information and examining whether the holdings information will affect fund performance. It is the writer’s hope that the study will be helpful to fund managers in making investment strategies, and increase the fund performance by controlling the volume of holdings.
The conclusions of this study are as followings: fund holdings do affect fund performance, and concentrate holdings make better performance cause of the reduced monitor cost. Moreover, the conclusion is the same in both bullish and bearish markets. At last but not least, no matter how big the funds size are, the conclusion is also supported the positive effect in fund performance of concentrate holdings.

中文文獻
1.王琮瑜，共同基金的類型、規模與其操作績效關係之研究，國立交通大學管理科學研究所未出版碩士論文，民國85年6月。
2.林世峻，”影響台灣股票型基金績效之特性因素研究”， 淡江大學/管理科學學系/民國88年6月。
3.辛穎琪，”臺灣股票型基金之績效評估:持股比率分析法”，國立政治大學財務管理研究所碩士論文，民國89年6月。唐仕玉，共同基金規模、資訊成本對報酬率之影響，國立台北大學企研所，民國88年6月。
4.洪嘉苓，共同基金經理團隊與基金績效關係之研究，國立中山大學/企業管理學系研究所，民國88年6月。
5.陳欣詠, 基金經理人選股因素與績效評估，國立中山大學/財務管理研究所，民國86年6月。
6.陳俊明，共同基金持股偏好之研究，國立中正大學/系所名稱: 財務金融學系，民國85年6月。
7.高妮瑋，機構投資人持股偏好與績效之研究，國立中正大學/會計學研究所，民國89年6月。
8.蔡曉慧，共同基金持股偏好與績效，國立中正大學/財務金融研究所，民國87年6月。
9.鄭桂娥, 由持股比率評估共同基金之績效--台灣封閉型基金之實證研究，國立中山大學/財務管理學系，民國83年6月

英文文獻
1.Dellva W.L & G..T. Olsen ,(1998) The relationship between mutual fund fees and expenses and their effects on performance, The Financial Review 33，pp.85~104
2.Dewit D.P.M.(1998) Naive diversification, Financial Analysts Journal 54,pp.95~100
3.Elton E.J. and M.J.Gruber (1977) Risk reduction and portfolio size:An analystical solution, The journal of business 50 ,pp.415~437
4.Evans J.L and S.H. Archer (1968) ,Diversification and the reduction of dispersion.. Anempirical analysis,The Journal of Finance 23, pp.761~767
5.Ferr,S.& D.Chance (1987) The dffects of 12b-1 on mutual fund expense ratios:a note.The Journal of Finance 42,pp.1077~1082.
6.Fisher L and J.H.Lorie (1970) Some studies of variability of reduction of dispersion:An empirical analysis, The Jornal of Business 43,pp.99~134
7.Grossman ,S.&S.Stiglitz (1980). On the impossibility of informational efficient markets. American Economic Review 70,pp.393-408.
8.Hany A. Shawky , David M. Smith (2005) “Optimal Number of Stock Holdings in Mutual FundPortfolios Based on Market Performance The Financial Review ,pp.481~p495
9.Ibbotson, R.G.and P.D Kaplan (2000) Does asset allocation policy explain 40, 90,or 100 percent of performance? Financial analysts Journal 56, pp.26~33
10.Jacob, N.L.a Limited-Diversification Portfolio Selection Model for Small Investor.Journal of Finance ,29 pp.837~857
11.Markowitz H. (1959) Portfolio selection:Efficient Diversification of Investments(Wiley, New York)
12.O’Neal E.S. (1997) How many mutual funds constitute a diversified portfolio?Financial Analysts Journal 53,pp.37~46
13.Statman M,1987 How many mutual funds constitue a diversified portfolio? Financial and Quanitative Analysis 22, pp.353~363
14.Stowe, J.D., B.D. Jordan and S.D.Jordan,(1988) Measuring Mutual Fund Portfolio Turnover and Concentration .Working Paper, University of Missouri-Columbia.