Speculative Trading and Market Performance:
The Effect of Arbitrageurs on Efficiency and Market
Power in the New York Electricity Market
Celeste Saravia, University of California, Berkeley, Department of Economics
While the effect speculators have on forward premiums (the difference
between forward and expected spot prices) has been widely studied, there
has been very little focus on the effect speculators have on competition
in the product market. I study the effect speculators have had on production
decisions and price levels in New York's deregulated electricity market.
For the past two years of its operation, the market, which opened in November
1999, restricted trade to producers and retailers of electricity. During
this period, the forward price of electricity in western New York was
significantly higher than the expected spot price. I show that, after
the market opened to purely speculative traders the forward premium significantly
decreased. In addition, the forward price of transmission (the price difference
between two geographically distinct points) ceased to differ significantly
from the expected spot price of transmission. I present a theoretical
model to help understand these price relationships and other possible
effects of speculators on market prices and firms' production decisions.
Absent speculators, the model predicts that firms with market power will
price discriminate between the forward and spot markets for electricity,
resulting in the forward price being higher than the expected spot price.
This discrimination in the market for electricity will result in the forward
price of transmission under-predicting the spot price of transmission.
When speculators that prevent firms from price discriminating are added
to the model forward price-cost margins decrease. Using detailed data
on the marginal costs of generation units in New York, I test these predictions
of the model, and find that, after controlling for other market changes,
the forward price-cost margins of firms in western New York did, in fact,
significantly decrease after speculators were allowed to enter the market.
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