Wall Street has suffered a fresh bout of jitters over the stability of US conglomerate Tyco, as investors continue to shun firms perceived as resembling energy failure Enron.

Tyco, a complex network of companies in sectors from fire alarm systems to medical equipment, issued a profits warning on Wednesday, causing a 5% fall in its share price.

Tyco's shares have lost half their value this year, because investors are nervous of companies whose accounts they find opaque or confusing.

It has made more than 200 acquisitions in the past three years, and its books have been complicated by a web of legimitate but bewildering tax-avoidance schemes.

The profit warning was not received entirely negatively, however: analysts gave the firm credit for being open about its performance - not something it has been noted for in the past.

Strategy worries

Tyco still expects to make a healthy profit in the current quarter-year.

Mr Kozlowski no longer enjoys complete trust

But there are mounting concerns over its strategy, which now includes a plan to split the firm into four parts in an effort to release shareholder value.

For years, the company has produced above-market returns from unglamorous businesses, and investors have been happy to trust charismatic chairman Dennis Kozlowski to make the decisions for them.

After Enron's collapse, the mood has turned against companies with complicated accounting habits, and which have high-profile leaders such as Mr Kozlowski.

Shareholders are angry that Mr Kozlowski and Mark Swartz, Tyco's chief financial officer, have reportedly sold shares worth some $500m in the past three years, without informing the markets.

Counting the cost

Tyco is far from being a scandal along the lines of Enron, or Global Crossing, the ambitious US telecoms firm that collapsed last month.

But ominously, banks are already starting to count their exposure to the firm.

According to reports in the Wall Street Journal, JP Morgan Chase has unsecured Tyco loans worth $700m-1bn, the single biggest bank exposure to the firm.

JP Morgan was also one of the main bankers to Enron.