MANILA, Dec 21 (Reuters) - The Philippine Stock Exchange (PSE) said on Wednesday there was no indication of fraudulent trading in PLDT Inc shares before the company's disclosure of budget overruns, with most of the deals carried out by institutional traders.

"Just to assure you, without going to specifics, we did not see any indication of any fraudulent trades prior to the disclosure," PSE President and CEO Ramon Monzon told ANC, citing the outcome of an internal investigation.

PLDT's share price dropped more than 19% on Monday, extending a 4.2% decline on Friday, triggered by a selloff ahead of the company's disclosure of budget overruns totalling 48 billion pesos ($870.04 million) over the past years.

The Securities and Exchange Commission (SEC) said on Monday it has started an investigation into the selloff, and that it had ordered the PSE to submit initial reports on its own inquiry.

"We looked at buying and selling and basically, a lot of transactions are institutional trades, not personal trades and mostly by foreign brokers," Monzon said, adding the PSE was including in its probe PLDT trades from October.

PLDT's chief financial officer sits on the PSE board.

In a statement sent to the media on Wednesday, PLDT said it "will continue to cooperate fully" with regulators.

Shares in PLDT, which is partly owned by Japan's NTT DoCoMo Inc and Hong Kong's First Pacific Co, were up more than 5.0% as of 0705 GMT. ($1 = 55.1700 Philippine pesos) (Reporting by Karen Lema; Additional reporting by Neil Jerome Morales; Editing by Kanupriya Kapoor)