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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