X-Inefficiency
The failure to minimize costs or maximize returns. (Sometimes referred to as X-efficiency, but carrying the same meaning.

Yankee Bond
A dollar bond issued by a non-U.S. borrower in the United States.

YEN
The currency of Japan. Its subdivisions are 100 sen and 1000 rin.

Yield
The annual return, expressed as a percentage, of an investments value or cost. E.g., if an investment cost $1000 and returns $100, its yield equals 10%.

Yield to Call
The annual return, expressed as a percentage, of a bond or note if it is redeemed at the first possible call.

Yield to Maturity
The annual return, expressed as a percentage, of a bond or note redeemed at maturity.

YTD
Year To Date; meaning the period beginning of the calendar year, January 1st of the current year, or the fiscal year up until today's date

Zero Based Budget
Is where the expenses or costs of the prior year are not taken into consideration when establishing expense or budgetary levels looking forward. Each expense category starts from zero. All expenses or cost levels within the budget must be justified or re-justified as being necessary; thus “zero-base”.

Zero-Coupon Bond
A bond issued without coupons and without a statement of its rate of interest.

Zero-Coupon Security
A security that pays no interest until maturity, when the interest is paid in a lump sum.

Zero-Rated
Denotes goods on which the buyer pays no value-added tax although the seller can claim back any tax he/she has paid.