OPINION OF THE COURT
Balio, J. The parties physically separated in September of 1986. At that time, defendant mother left the marital residence. The two children of the marriage, a daughter five years of age and a son 10 months old, remained with the father in the marital residence. The parties were divorced in August of 1987. The judgment of divorce incorporated without merger the parties’ stipulation providing for joint custody of their two children, with primary physical custody to remain with the father and liberal visitation privileges to the mother. In August 1991, Supreme Court granted the mother’s motion for a change of primary physical custody.
The party seeking a change of custody "bears a heavy burden of proof that the change contemplated is in the child’s best interests” (Collins v Collins, 115 AD2d 979). Among the factors or circumstances to be considered in ascertaining the child’s best interests are: (1) the continuity and stability of the existing custodial arrangement, including the relative fitness of the parents and the length of time the present custodial arrangement has continued; (2) quality of the child’s home environment and that of the parent seeking custody; (3) the ability of each parent to provide for the child’s emotional and intellectual development; (4) the financial status and ability of each parent to provide for the child; (5) the individual needs and expressed desires of the child; and (6) the need of the child to live with siblings (see, Matter of Louise E.S. v W. Stephen S., 64 NY2d 946; Eschbach v Eschbach, 56 NY2d 167, 172-173; Matter of Nehra v Uhlar, 43 NY2d 242, 250-251; Matter of Ebert v Ebert, 38 NY2d 700, 702-704; Matter of Blake v Blake, 106 AD2d 916).
The preexisting custodial arrangement, whether established by agreement or order, is a weighty factor, and the existing arrangement should be changed based only upon *211" 'countervailing circumstances on consideration of the totality of circumstances’ ” (Friederwitzer v Friederwitzer, 55 NY2d 89, 95). The priority accorded the existing arrangement reflects the view that custody of children should be established on a long-term basis, wherever possible, and that "children should not be shuttled back and forth between divorced parents merely because of changes in marital status, economic circumstances or improvements in moral or psychological adjustment” (Obey v Degling, 37 NY2d 768, 770; see also, Matter of Nehra v Uhlar, 43 NY2d 242, 251, supra; Keating v Keating, 147 AD2d 675, 677, lv dismissed 74 NY2d 791; Martin v Martin, 74 AD2d 419, 426). Thus, a long-term custodial arrangement established by agreement should prevail "unless it is demonstrated that the custodial parent is unfit or perhaps less fit” (Martin v Martin, supra, at 426; see also, Obey v Degling, supra, at 770; Alan G. v Joan G, 104 AD2d 147, 153), and such established custodial arrangement should not be changed solely to accommodate the desires of the child (see, Matter of Ebert v Ebert, 38 NY2d 700, 703, supra).
In the instant case, it is clear that the trial court changed custody of both children because of the "strong desires” of the 10-year-old daughter to live with her mother and because of the close relationship between the siblings. This was improper. A child of 10 or 11 years of age generally is not of sufficient maturity to weigh intelligently the factors essential to making a wise choice as to custody (Matter of Robert T.F. v Rosemary F., 148 AD2d 449, 452; Feltman v Feltman, 99 AD2d 540, 541; Matter of Hahn v Falce, 56 Misc 2d 427, 435). Moreover, the trial court acted without the benefit of an investigative report and without the testimony of teachers, counselors, psychologists or other experts (see, Matter of Mead v Mead, 143 AD2d 454; Matter of Calder v Woolverton, 50 AD2d 587, affd 39 NY2d 1042; Matter of Barry v Glynn, 59 Misce 2d 75 [child’s preference given effect where supported by expert testimony of psychologist and detailed probation reports]). The record, therefore, is devoid of evidence that this 10 year old is possessed of exceptional judgment or maturity to decide her custodial fate or that her strong preference to be with her mother is in her best interests.
Ordinarily, the custody determination of the trial court is entitled to great deference (see, Eschbach v Eschbach, 56 NY2d 167, 173, supra; Martin v Martin, 74 AD2d 419, 425, supra). Such deference is not warranted, however, where the custody determination lacks a sound and substantial basis in *212the record (see, Keating v Keating, 147 AD2d 675, 677, supra; Matter of Gloria S. v Richard B., 80 AD2d 72, 76). In the instant case, the trial court, by effectively permitting the 10-year-old daughter to dictate the custody arrangement for herself and her brother, failed to weigh properly all of the factors and circumstances bearing on the children’s best interests. We further conclude that those factors other than the weighty, but not conclusive, circumstances of the existing custodial arrangement, do not demonstrate "countervailing circumstances” supporting a change of custody. Accordingly, the order should be reversed.
There is no question that the daughter has expressed a strong preference to reside with her mother. The daughter expressed discontent with the fact that her grandmother talked poorly of her mother and that she had chores to do for her grandmother. The grandmother’s reference to the mother was one isolated event, however, and the importance of this event was discounted by the Law Guardian. The father is somewhat conservative in attitude and approach, and it is evident that he is the more strict disciplinarian. Unfortunately, there is no expert testimony or report to measure the influence of discipline and the newness of the mother’s home and environment upon the daughter’s preference. In any event, the trial court found that both parties were fit parents and made no finding that one parent was more or less fit than the other. The record supports that finding. There is no evidence that one parent has an appreciably greater financial ability to provide for the children than the other parent. The daughter is doing very well academically, and the son is progressing well in the early stages of his education. There is no evidence that a change of custody will enhance the children’s educational development. The children have continuously resided in the father’s home in Naples, New York, where each child has a separate bedroom. During overnight visitations at her mother’s residence, which the mother occupies with her current husband and her husband’s six-year-old son, the daughter sleeps in the same bedroom with her brother and her stepbrother. Although the mother and her husband were in the process of constructing a separate bedroom for the daughter, the Law Guardian properly considered the current situation unsuitable. Because of the father’s work schedule, the children’s paternal grandmother arrives at the father’s house early each weekday morning to get the children ready for school and is there during after-school hours until *213the father returns from work. Because of the work schedules of the mother and her husband, the children would be readied for school by the husband’s father. The Law Guardian expressed concern about the ability of the husband’s father to care for the children. Additionally, the mother and her husband frequently work on weekends; plaintiff father does not. Finally, the record is devoid of evidence that the relationship of the children is so close that they should not be separated. The sole basis for that finding by the trial court is a conclusory statement by the Law Guardian, and it appears that the statement was based on matters dehors the record.
In sum, the record does not support a finding that the strong preference of the 10-year-old daughter to live with her mother would be in her best interests, and the expressed desire of the daughter is not a sufficient basis for changing her custodial circumstance (see, Matter of Ebert v Ebert, 38 NY2d 700, 703, supra; Feltman v Feltman, 99 AD2d 540, supra; Martin v Martin, 74 AD2d 419, supra) or for uprooting the son from the only primary caretaker he has ever known (see, Aberbach v Aberbach, 33 NY2d 592, 593; Keating v Keating, 147 AD2d 675, 678, supra; Alan G. v Joan G., 104 AD2d 147, 153, supra). Because there are no countervailing circumstances that would warrant a change in the custodial arrangement that has existed for the past five years, the trial court’s determination lacks a substantial basis and should be reversed.
After entry of the order appealed from, the trial court denied a stay of enforcement pending appeal. As a result, the children now are residing with the mother in a different school district. Where a change of custody has been directed, trial courts should be particularly sensitive to the impact that the denial of a stay might have upon the children should it ultimately be determined that the motion for a change of custody should not have been granted. In many instances, granting the stay, together with some time limitation upon perfection of the appeal, might avoid precipitous shuttling of the children back and forth between parents and school districts. Based upon the existing circumstance, primary custody of the children should be returned to the father upon conclusion of the school year, and this matter should be remitted to Supreme Court for the fixing of an appropriate visitation schedule.