Ms. Siy-Yap is Senior Vice President and the Chief Finance Officer of Meralco. She is a member of the Board of Directors of Republic Surety and Insurance Company, Inc. Clark Electric Philippines Meter and Instrument Company, Inc., CIS Bayad Center, Inc., Philippine Commercial Capital, Inc., MRail, Inc., Meralco PowerGen Corporation, Redondo Peninsula Energy, Inc., MPG Holdings Phils., Inc. and MPG Asia Limited. She is the President of Lighthouse Overseas Insurance Limited. She is a Trustee of the Meralco Pension Fund and One Meralco Foundation, Inc. and First Pacific Learning Academy, Inc. She is the Vice Chairman of the Board of Accountancy of the Professional Regulation Commission and a member of the Holdings Market Governance Board of the Philippine Dealing System Corporation. She was a Partner at SyCip Gorres
Velayo & Co. before joining Meralco.

Ms. Siy-Yap holds a Bachelor of Science in Business Administration and Accountancy degree from the University of the Philippines and a Masters in Business Administration from J.L. Kellog School of Management of Northwestern University and The Hong Kong University of Science and Technology.