Tác động giá của thông tin phát hành thêm cổ phiếu trên thị trường chứng khoán Việt Nam

# HflT TRI€N THi TRUONG VON

TAC DONG GIA CLIA THONG TIN PHAT HANH THEM CO PHIEU

TREN THI TRirdNG CHUNG KHOAN VIET NAM

TS. Nguyin Viet Dung

Dql hgc Ngogi thuang

Bai viit do ludng va giii thfch tac ddng gia cQa thdng tin phat hanh them c6 phiiu

tren thi trudng chiing khoan (TTCK) Viet Nam bang phuang phap nghien cUu stf kidn

(event study) va hoi quy dOlieu cheo. Kit qui nghidn cUu cho thay khi thi tnfdng di

Idn, phin Ung tich ci/c cQa gia c6 phiiu chQ yiu do ky vgng cQa cac nha dau tulen

rit cao va khi dd nhiirng yiu toco bin khdrig giif nhieu vai trd. Ngugc lai, khi thi trudng

di xuong, tac ddng tidu cue din gia cd dau hidu chju su chi phoi cQa quy luat cung

cau. Ngoai ra, mUc gia phat hanh cung la mdt yiu to ciii tinh tdi tren TTCK Vidt^Nam^

do cac giao djch chuyen nhugng quyen mua chua phat triin d mUc do cao. Kit qua

nay cho thiy cin tiip tuc cac giii phap hoan thien hoat ddng cQa thj trudng do trong

ci hai trudng hgp nay, nguon luc deu khdng dugc phan bSmdt each toi uu, anh hudng

din vide dan vdn mdt each hidu qui cho nen kinh ti.

Mi Ipt van de di/dc

I doanh nghiep phat

hanh, nha dau ti/

cung nhi/ cac cap quan ly thi

tn/dng chumg khoan quan tam

la gia cd phieu bien dpng nhi/

the nao trudc thdng tin phat

hanh them. Nam di/pc phan

cmg gia cho phep cac thanh

phan tren hieu di/dc phan nao

khdng nhumg dpng thai cCia thi

trudng ma cdn cCicl ca doanh

nghiep phat hanh, tiS 66 cd

chidn lUdc phu hdp vdi vi tn

cCia hp.

Tac dpng gia cCia thdng tin

phat hanh them cd phieu cd

the giai thfch theo nhieu each,

anh hudng cCia bat can xumg

thdng tin (Myers & Majluf,

1984; Asquith & Mullins, 1986)

cung nhi/ cCia tfnh khdng hoan

hao trong 66 co gian cau cd

phieu (Bayless & Chaplinsky,

1996) cho tha'y gia se giam khi

phat hanh them cd phieu di/dc

thdng bao. Tuy nhien tren cac

thi trudng mdi ndi vdi nhieu cd

hpi dau tir tang tn/dng thi

thdng tin phat hanh them cd

tac dpng tfch cUc den gia (Tan,

Chng & Tong, 2002). Ngoai ra,

phan umg gia cung chju tac

dpng cCia yeu td quyen ldi cd

ddng (Adaoglu, 2006) va viec

tang tinh thanh khoan do cd

phieu dUdc sd hufu rpng rai

hdn... Tai Viet Nam, do mCfc

66 phat trien cCia TTCK cdn

thap, dli doan ve tac dpng gia

cCia phat hanh them, ngoai cac

ydu td tren, can tfnh tdi cac

van de phi cd ban khac. Qua

trinh phat trien cCia thj tnrdng

cho tha'y khi gia chCfng khoan

cd xu hudng di len, phat hanh

them cd phieu thudng di kem

vdi phan Cmg ra't tfch ciic cda

thj trudng va ngUdc lai trong

thdi ky gia xudng.

Do phat hanh them cd phieu

cd lien quan chat che den van

de tai trd cCia cac cdng ty niem

yet cung nhir hieu qua dau ti/

cCia cac nha dau ti/ ndi rieng

va sti van hanh cCia TTCK Viet

Nam ndi chung, nhat la trong

giai doan dang phat trien va

hoan thien hien nay, mpt

nghien cufU ve chO de nay la

rat can thiet. Tn/dc day, da cd

mpt sd phan tfch ve boat dpng

phat hanh them (Nguyen Thj

My Dung & LUdng Van Sinh,

2007; Nguyin Minh Phong,

2008; Ly Lam Duy & Mai Thi/.

2008...). Tuy nhien, dd mdi la

nhumg nghien cufu tdng quat

va djnh tfnh, khdng di sau vao

li/dng hda tac dpng gia cCia

thdng tin phat hanh them cung

nhi/ chi/a phan tfch cac yeu td

anh hi/dng den tac dpng nay.

Day la muc tieu chi'nh cCia bai

viet^

1. Do lirdng tac dpng gia

ciia phat hanh them cd

phieu tren TTCK Viet Nam

1.1. Phinmg phap nghien

Cliu sukiin (Event Studies)

Trong bai viet nay, phUdng

phap nghien cCfu sti kien dUdc

sijf dung de i/dc tfnh tac dpng

gia cCia thdng tin phat hanh

them cd phieu tren TTCK Viet

Nam. Theo ly thuyet tai chfnh,

gia cd phieu bien dpng do hai

yeu td he thdng va phi he

thdng. Yeu td he thdng tac

ddng Chung den toan bp cac

CO phieu cdn yeu td phi he

thdng la yeu td lien quan den

dac thu cCia tCmg cd phieu. Do

phat hanh them cd phieu la sif

kien cd tinh phi he thdng, de

xac djnh tac dpng cCia nd den

gia cd phieu can tach rieng

phan bien dpng do yeu td he

thdng. Phan bien dpng he

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