This empirical study of security issues by UK companies between 1959 and 1974 focuses on how companies select between financing instruments at a given point in time.It throws light on a number of interesting questions. First, it demonstrates that companies are heavily influenced by market conditions and the past history of security prices in choosing between debt and equity. Second, it provides evidence that companies appear to make their choice of financing instrument as if they have target levels of debt in mind. Finally, the results are consistent with the notion that these target debt levels are themselves a function of company size, bankruptcy risk, and asset composition. AN IMPORTANT QUESTION FACING companies in need ofnew finance is whether * London Business School, London. I would like to thank Professor Richard Brealey, Dr. Ian Cooper, and participants at the London Business School Finance Workshop for their very useful comments and suggestions. 121 122 The Journal of Finance I. Theoretical Background In principal, companies needing new finance should issue equity if they are above their target debt level and debt if they are below. With no flotation costs, such adjustments could be made instantaneously and continuously. In practice however, the existence of significant flotation costs means that companies should plan issues to minimize both flotation costs and the costs of deviating from their target ratio. This gives rise to infrequent "lumpy" issues, with debt ratios over time fluctuating around their target.' Clearly, in any empirical work, it is important to identify what this target level is. However, since it is unobservable, we can do this only by looking at past behavior or by turning to the theory of capital structure for help. Unfortunately the theory provides only limited guidance. More than twenty years after Modigliani and Miller's [26] original article, the theoretical debate is still centered on the most fundamental of issues. There are, nevertheless, two points of broad agreement. First, in spite of fundamental differences about the way in which it is important, virtually everyone stresses the importance of tax.2 Second, most people would accept that managers are likely to set debt levels with due regard to the expected costs of bankruptcy and financial distress.3 The implications for target debt levels and hence issue behavior are clear. First, any overall change in tax levels could cause issuing companies to shift their preferences towards either debt or equity. This will be true regardless of whether this is a temporary effect lasting only until equilibrium is restored (see Miller [25]), or whether it represents a permanent shift in companies' target ratios.4 Second, target debt levels will be influenced by the probability of financial distress. Since the latter is a function of both operating and financial risk, it seems reasonable to expect companies with high operating risk to use less debt.Given the incomplete and somewhat unsatisfactory state of the theory, little more can be sai...

Abstract— The recently published phylogeny of Braconidae by Quicke and van Achterberg is reassessed. Character‐state definitions and character polarities are evaluated, and more rigorous methods are suggested. Our results indicate that there are many more parsimonious solutions to their data set, the consensus of which differs substantially from their results. Based on our reassessment, little can be said about the relationships among braconid subfamilies. Consensus trees show the cyclostomes as a largely unresolved basal grade. The two other major lineages which have been proposed, the helconoids and microgastroids, are somewhat better resolved, but not consistently so. Relationships among the helconoids vary considerably depending on the parameters used for parsimony analysis.

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The systematics of the hymenopterous parasitoids associated with Phoracantha spp. in Australia are reviewed. An illustrated key to species is presented to facilitate their identification as part of ongoing attempts for the biological control of P. semipunctata (Fabricius), an exotic pest on eucalypt trees. Information on the taxonomy, distribution and biology of 18 species of primary and hyperparasitoids associated with Phoracantha spp. are presented. A new braconid genus, Jarra, is described to accommodate three new species, /. phoracantha, }. maculipennis and /. bicolor, and Doryctes diadoxi Nixon (Doryctinae), the latter associated with a buprestid host. Two other new species, Heterospilus nukunu (Doryctinae) and Callibracon moorei (Braconinae) are also described; Iphiaulax morleyi Froggatt is synonymized with Atanycolus tomentosus Szepligeti and I. rubriceps Froggatt is synonymized with Syngaster lepidus Brulle; lectotypes are designated for /. morleyi, I. rubriceps and /. phoracanthae Froggatt; and Ipobracon flaviceps flaviceps (Cameron) and I. flaviceps mackayensis Turner are transferred to Callibracon. The encyrtid genus Aventianella is recorded from Australia for the first time and the egg parasitoid of P. semipunctata, A. longoi Siscaro described from Italy, is postulated to be endemic to Australia.