* Techs surge, LG Elec up 2.3 percent
* Apple supplier LG Display up before Q1 results
* KAI surges on 1.2 trillion won in Boeing orders
* STX affiliates plunge on local media reports
By Somang Yang
SEOUL, April 22 (Reuters) - South Korean shares closed higher on Monday as techs rebounded ahead of earnings reports, which kicked off with LG Display later in the afternoon.
The Korea Composite Stock Price Index (KOSPI) closed up 1 percent at 1,926.31 points, posting the biggest daily gain since March 25, but still down 3.9 percent so far this month.
The tech sub-index rose 1.8 percent, accounting for 0.5 percent of the KOSPI’s gains.
“Samsung and LG are up on expectations that smartphone demand will continue to be strong,” said Do Hyun-woo, an analyst for Mirae Asset Securities.
“Meanwhile, semiconducter makers are expected to benefit from the rising price of D-RAM chips as supply will be tight.”
Shares in Samsung Electronics were up 1.9 percent while LG Electronics rose 2.3 percent.
Shares in LG Display closed 2.2 percent higher shortly before it released earnings. The panel maker posted a small and slightly higher than expected quarterly profit, but concerns remained about the outlook for Apple Inc, its biggest customer.
Korea Aerospace Industries (KAI) jumped 6 percent after reporting orders totalling 1.2 trillion won ($1.08 billion) from Boeing for parts for the Dreamliner (787) and B737 jets and for AH-64E Apache Guardian helicopters.
On the downside, STX affiliates such as STX Corp and STX Heavy Industries plummeted after a local media report that STX Offshore & Shipbuilding may sell foreign assets and lay off up to half of its workforce to pay back its creditors.
Overall, 525 shares advanced while 283 declined.
Local institutions bought a net 20 billion won ($17.92 million) worth of KOSPI shares, buttressing the main board, but just 255,781 shares traded hands, making the session the thinnest since Aug 6.
The KOSPI 200 benchmark of core stocks closed up 1.1 percent, while the junior KOSDAQ edged 1 percent higher.
Move on day +1.03 percent
12-month high 2,031.10 2 January 2013
12-month low 1,769.31 25 July 2012
Change on yr -3.54 percent
All-time high 2,231.47 27 April 2011
All-time low 93.10 6 January 1981 ($1 = 1116.2500 Korean won) (Editing by Kim Coghill)